diff --git a/PDelays.cc b/PDelays.cc
index c51c1f5df..40ea8b262 100644
--- a/PDelays.cc
+++ b/PDelays.cc
@@ -55,12 +55,14 @@ void PDelays::set_delay(PExpr*del)
 }
 
 
-void PDelays::set_delays(const svector<PExpr*>*del, bool df)
+void PDelays::set_delays(const list<PExpr*>*del, bool df)
 {
       assert(del);
-      assert(del->count() <= 3);
-      for (unsigned idx = 0 ;  idx < del->count() ;  idx += 1)
-	    delay_[idx] = (*del)[idx];
+      assert(del->size() <= 3);
+
+      list<PExpr*>::const_iterator cur = del->begin();
+      for (unsigned idx = 0 ;  cur != del->end() ;  idx += 1, ++cur)
+	    delay_[idx] = *cur;
 
       delete_flag_ = df;
 }
diff --git a/PDelays.h b/PDelays.h
index 78a764f36..00e061807 100644
--- a/PDelays.h
+++ b/PDelays.h
@@ -21,6 +21,7 @@
 
 # include  "svector.h"
 # include  <string>
+# include  <list>
 # include  <iostream>
 
 #ifdef __GNUC__
@@ -48,7 +49,7 @@ class PDelays {
 	   this object takes ownership of the expressions, and will
 	   delete it in the destructor. */
       void set_delay(PExpr*);
-      void set_delays(const svector<PExpr*>*del, bool delete_flag=true);
+      void set_delays(const list<PExpr*>*del, bool delete_flag=true);
 
       unsigned delay_count() const;
 
diff --git a/PExpr.cc b/PExpr.cc
index 98617deff..35ec1b336 100644
--- a/PExpr.cc
+++ b/PExpr.cc
@@ -26,6 +26,7 @@
 # include  "PWire.h"
 # include  "Module.h"
 # include  "netmisc.h"
+# include  "util.h"
 # include  <typeinfo>
 
 PExpr::PExpr()
@@ -161,14 +162,24 @@ PECallFunction::PECallFunction(perm_string n)
 }
 
 // NOTE: Anachronism. Try to work all use of svector out.
-PECallFunction::PECallFunction(const pform_name_t&n, const svector<PExpr *> &parms)
-: path_(n), parms_(vector_from_svector(parms))
+PECallFunction::PECallFunction(const pform_name_t&n, const list<PExpr *> &parms)
+: path_(n), parms_(parms.size())
 {
+      int tmp_idx = 0;
+      assert(parms_.size() == parms.size());
+      for (list<PExpr*>::const_iterator idx = parms.begin()
+		 ; idx != parms.end() ; ++idx)
+	    parms_[tmp_idx++] = *idx;
 }
 
-PECallFunction::PECallFunction(perm_string n, const svector<PExpr*>&parms)
-: path_(pn_from_ps(n)), parms_(vector_from_svector(parms))
+PECallFunction::PECallFunction(perm_string n, const list<PExpr*>&parms)
+: path_(pn_from_ps(n)), parms_(parms.size())
 {
+      int tmp_idx = 0;
+      assert(parms_.size() == parms.size());
+      for (list<PExpr*>::const_iterator idx = parms.begin()
+		 ; idx != parms.end() ; ++idx)
+	    parms_[tmp_idx++] = *idx;
 }
 
 PECallFunction::~PECallFunction()
@@ -191,9 +202,14 @@ bool PECallFunction::has_aa_term(Design*des, NetScope*scope) const
       return flag;
 }
 
-PEConcat::PEConcat(const svector<PExpr*>&p, PExpr*r)
-: parms_(p), tested_widths_(p.count()), repeat_(r)
+PEConcat::PEConcat(const list<PExpr*>&p, PExpr*r)
+: parms_(p.size()), tested_widths_(p.size()), repeat_(r)
 {
+      int tmp_idx = 0;
+      assert(parms_.size() == p.size());
+      for (list<PExpr*>::const_iterator idx = p.begin()
+		 ; idx != p.end() ; ++idx)
+	    parms_[tmp_idx++] = *idx;
 }
 
 PEConcat::~PEConcat()
@@ -203,7 +219,7 @@ PEConcat::~PEConcat()
 
 void PEConcat::declare_implicit_nets(LexicalScope*scope, NetNet::Type type)
 {
-      for (unsigned idx = 0 ; idx < parms_.count() ; idx += 1) {
+      for (unsigned idx = 0 ; idx < parms_.size() ; idx += 1) {
 	    parms_[idx]->declare_implicit_nets(scope, type);
       }
 }
@@ -211,7 +227,7 @@ void PEConcat::declare_implicit_nets(LexicalScope*scope, NetNet::Type type)
 bool PEConcat::has_aa_term(Design*des, NetScope*scope) const
 {
       bool flag = false;
-      for (unsigned idx = 0 ; idx < parms_.count() ; idx += 1) {
+      for (unsigned idx = 0 ; idx < parms_.size() ; idx += 1) {
 	    flag = parms_[idx]->has_aa_term(des, scope) || flag;
       }
       if (repeat_)
diff --git a/PExpr.h b/PExpr.h
index 6141f6cc9..6c3b68022 100644
--- a/PExpr.h
+++ b/PExpr.h
@@ -160,7 +160,7 @@ ostream& operator << (ostream&, const PExpr&);
 class PEConcat : public PExpr {
 
     public:
-      PEConcat(const svector<PExpr*>&p, PExpr*r =0);
+      PEConcat(const list<PExpr*>&p, PExpr*r =0);
       ~PEConcat();
 
       virtual verinum* eval_const(Design*des, NetScope*sc) const;
@@ -187,7 +187,7 @@ class PEConcat : public PExpr {
       NetNet* elaborate_lnet_common_(Design*des, NetScope*scope,
 				     bool bidirectional_flag) const;
     private:
-      svector<PExpr*>parms_;
+      vector<PExpr*>parms_;
       std::valarray<unsigned>tested_widths_;
 
       PExpr*repeat_;
@@ -661,8 +661,8 @@ class PECallFunction : public PExpr {
       explicit PECallFunction(perm_string n);
 
 	// svector versions. Should be removed!
-      explicit PECallFunction(const pform_name_t&n, const svector<PExpr *> &parms);
-      explicit PECallFunction(perm_string n, const svector<PExpr *> &parms);
+      explicit PECallFunction(const pform_name_t&n, const list<PExpr *> &parms);
+      explicit PECallFunction(perm_string n, const list<PExpr *> &parms);
 
       ~PECallFunction();
 
diff --git a/PGate.cc b/PGate.cc
index ae64a4c48..9ec25d33f 100644
--- a/PGate.cc
+++ b/PGate.cc
@@ -24,29 +24,42 @@
 # include  "verinum.h"
 # include  <cassert>
 
-PGate::PGate(perm_string name,
-	     svector<PExpr*>*pins,
-	     const svector<PExpr*>*del)
-: name_(name), pins_(pins)
+void PGate::set_pins_(list<PExpr*>*pins)
 {
+      assert(pins);
+      assert(pins->size() == pins_.size());
+
+      for (size_t idx = 0 ; idx < pins_.size() ; idx += 1) {
+	    pins_[idx] = pins->front();
+	    pins->pop_front();
+      }
+
+      assert(pins->empty());
+      delete pins;
+}
+
+PGate::PGate(perm_string name, list<PExpr*>*pins, const list<PExpr*>*del)
+: name_(name), pins_(pins? pins->size() : 0)
+{
+      if (pins) set_pins_(pins);
       if (del) delay_.set_delays(del);
       str0_ = IVL_DR_STRONG;
       str1_ = IVL_DR_STRONG;
 }
 
-PGate::PGate(perm_string name,
-	     svector<PExpr*>*pins,
-	     PExpr*del)
-: name_(name), pins_(pins)
+PGate::PGate(perm_string name, list<PExpr*>*pins, PExpr*del)
+: name_(name), pins_(pins? pins->size() : 0)
 {
+      if (pins) set_pins_(pins);
       if (del) delay_.set_delay(del);
       str0_ = IVL_DR_STRONG;
       str1_ = IVL_DR_STRONG;
 }
 
-PGate::PGate(perm_string name, svector<PExpr*>*pins)
-: name_(name), pins_(pins)
+PGate::PGate(perm_string name, list<PExpr*>*pins)
+: name_(name), pins_(pins? pins->size() : 0)
 {
+      if (pins) set_pins_(pins);
       str0_ = IVL_DR_STRONG;
       str1_ = IVL_DR_STRONG;
 }
@@ -104,16 +117,16 @@ unsigned PGate::delay_count() const
       return delay_.delay_count();
 }
 
-PGAssign::PGAssign(svector<PExpr*>*pins)
+PGAssign::PGAssign(list<PExpr*>*pins)
 : PGate(perm_string(), pins)
 {
-      assert(pins->count() == 2);
+      assert(pin_count() == 2);
 }
 
-PGAssign::PGAssign(svector<PExpr*>*pins, svector<PExpr*>*dels)
+PGAssign::PGAssign(list<PExpr*>*pins, list<PExpr*>*dels)
 : PGate(perm_string(), pins, dels)
 {
-      assert(pins->count() == 2);
+      assert(pin_count() == 2);
 }
 
 PGAssign::~PGAssign()
@@ -121,14 +134,14 @@ PGAssign::~PGAssign()
 }
 
 PGBuiltin::PGBuiltin(Type t, perm_string name,
-		     svector<PExpr*>*pins,
-		     svector<PExpr*>*del)
+		     list<PExpr*>*pins,
+		     list<PExpr*>*del)
 : PGate(name, pins, del), type_(t), msb_(0), lsb_(0)
 {
 }
 
 PGBuiltin::PGBuiltin(Type t, perm_string name,
-		     svector<PExpr*>*pins,
+		     list<PExpr*>*pins,
 		     PExpr*del)
 : PGate(name, pins, del), type_(t), msb_(0), lsb_(0)
 {
@@ -246,7 +259,7 @@ const char* PGBuiltin::gate_name() const
       return "<unknown>";
 }
 
-PGModule::PGModule(perm_string type, perm_string name, svector<PExpr*>*pins)
+PGModule::PGModule(perm_string type, perm_string name, list<PExpr*>*pins)
 : PGate(name, pins), overrides_(0), pins_(0),
   npins_(0), parms_(0), nparms_(0), msb_(0), lsb_(0)
 {
@@ -265,7 +278,7 @@ PGModule::~PGModule()
 {
 }
 
-void PGModule::set_parameters(svector<PExpr*>*o)
+void PGModule::set_parameters(list<PExpr*>*o)
 {
       assert(overrides_ == 0);
       overrides_ = o;
diff --git a/PGate.h b/PGate.h
index 3f4cceaf0..6de2c3f58 100644
--- a/PGate.h
+++ b/PGate.h
@@ -26,6 +26,8 @@
 # include  "PDelays.h"
 # include  "netlist.h"
 # include  <map>
+# include  <list>
+# include  <vector>
 # include  <string>
 class PExpr;
 class PUdp;
@@ -48,13 +50,13 @@ class Module;
 class PGate : public LineInfo {
 
     public:
-      explicit PGate(perm_string name, svector<PExpr*>*pins,
-		     const svector<PExpr*>*del);
+      explicit PGate(perm_string name, list<PExpr*>*pins,
+		     const list<PExpr*>*del);
 
-      explicit PGate(perm_string name, svector<PExpr*>*pins,
+      explicit PGate(perm_string name, list<PExpr*>*pins,
 		     PExpr*del);
 
-      explicit PGate(perm_string name, svector<PExpr*>*pins);
+      explicit PGate(perm_string name, list<PExpr*>*pins);
 
       virtual ~PGate();
 
@@ -70,8 +72,8 @@ class PGate : public LineInfo {
 
       unsigned delay_count() const;
 
-      unsigned pin_count() const { return pins_? pins_->count() : 0; }
-      PExpr*pin(unsigned idx) const { return (*pins_)[idx]; }
+      unsigned pin_count() const { return pins_.size(); }
+      PExpr*pin(unsigned idx) const { return pins_[idx]; }
 
       ivl_drive_t strength0() const;
       ivl_drive_t strength1() const;
@@ -87,7 +89,7 @@ class PGate : public LineInfo {
       virtual bool elaborate_sig(Design*des, NetScope*scope) const;
 
     protected:
-      const svector<PExpr*>& get_pins() const { return *pins_; }
+      const vector<PExpr*>& get_pins() const { return pins_; }
 
       void dump_pins(ostream&out) const;
       void dump_delays(ostream&out) const;
@@ -95,10 +97,12 @@ class PGate : public LineInfo {
     private:
       perm_string name_;
       PDelays delay_;
-      svector<PExpr*>*pins_;
+      vector<PExpr*>pins_;
 
       ivl_drive_t str0_, str1_;
 
+      void set_pins_(list<PExpr*>*pins);
+
     private: // not implemented
       PGate(const PGate&);
       PGate& operator= (const PGate&);
@@ -111,8 +115,8 @@ class PGate : public LineInfo {
 class PGAssign  : public PGate {
 
     public:
-      explicit PGAssign(svector<PExpr*>*pins);
-      explicit PGAssign(svector<PExpr*>*pins, svector<PExpr*>*dels);
+      explicit PGAssign(list<PExpr*>*pins);
+      explicit PGAssign(list<PExpr*>*pins, list<PExpr*>*dels);
       ~PGAssign();
 
       void dump(ostream&out, unsigned ind =4) const;
@@ -143,10 +147,10 @@ class PGBuiltin  : public PGate {
 
     public:
       explicit PGBuiltin(Type t, perm_string name,
-			 svector<PExpr*>*pins,
-			 svector<PExpr*>*del);
+			 list<PExpr*>*pins,
+			 list<PExpr*>*del);
       explicit PGBuiltin(Type t, perm_string name,
-			 svector<PExpr*>*pins,
+			 list<PExpr*>*pins,
 			 PExpr*del);
       ~PGBuiltin();
 
@@ -189,7 +193,7 @@ class PGModule  : public PGate {
 	// If the binding of ports is by position, this constructor
 	// builds everything all at once.
       explicit PGModule(perm_string type, perm_string name,
-			svector<PExpr*>*pins);
+			list<PExpr*>*pins);
 
 	// If the binding of ports is by name, this constructor takes
 	// the bindings and stores them for later elaboration.
@@ -201,7 +205,7 @@ class PGModule  : public PGate {
 
 	// Parameter overrides can come as an ordered list, or a set
 	// of named expressions.
-      void set_parameters(svector<PExpr*>*o);
+      void set_parameters(list<PExpr*>*o);
       void set_parameters(named<PExpr*>*pa, unsigned npa);
 
 	// Modules can be instantiated in ranges. The parser uses this
@@ -219,7 +223,7 @@ class PGModule  : public PGate {
 
     private:
       perm_string type_;
-      svector<PExpr*>*overrides_;
+      list<PExpr*>*overrides_;
       named<PExpr*>*pins_;
       unsigned npins_;
 
diff --git a/PTask.h b/PTask.h
index 949c6d20c..df1dee628 100644
--- a/PTask.h
+++ b/PTask.h
@@ -24,6 +24,7 @@
 # include  "svector.h"
 # include  "StringHeap.h"
 # include  <string>
+# include  <list>
 class Design;
 class NetScope;
 class PWire;
@@ -44,7 +45,7 @@ enum PTaskFuncEnum {
 
 struct PTaskFuncArg {
       PTaskFuncEnum type;
-      svector<PExpr*>*range;
+      vector<PExpr*>*range;
 };
 
 /*
diff --git a/Statement.cc b/Statement.cc
index fc6670e38..88581712f 100644
--- a/Statement.cc
+++ b/Statement.cc
@@ -114,14 +114,26 @@ void PBlock::set_statement(const svector<Statement*>&st)
       list_ = st;
 }
 
-PCallTask::PCallTask(const pform_name_t&n, const svector<PExpr*>&p)
-: path_(n), parms_(p)
+PCallTask::PCallTask(const pform_name_t&n, const list<PExpr*>&p)
+: path_(n), parms_(p.size())
 {
+      list<PExpr*>::const_iterator cur = p.begin();
+      for (size_t idx = 0 ; idx < parms_.size() ; idx += 1) {
+	    parms_[idx] = *cur;
+	    ++cur;
+      }
+      assert(cur == p.end());
 }
 
-PCallTask::PCallTask(perm_string n, const svector<PExpr*>&p)
-: parms_(p)
+PCallTask::PCallTask(perm_string n, const list<PExpr*>&p)
+: parms_(p.size())
 {
+      list<PExpr*>::const_iterator cur = p.begin();
+      for (size_t idx = 0 ; idx < parms_.size() ; idx += 1) {
+	    parms_[idx] = *cur;
+	    ++cur;
+      }
+      assert(cur == p.end());
       path_.push_back(name_component_t(n));
 }
 
diff --git a/Statement.h b/Statement.h
index f358ae7e0..ef6f2b22d 100644
--- a/Statement.h
+++ b/Statement.h
@@ -20,6 +20,7 @@
  */
 
 # include  <string>
+# include  <list>
 # include  "ivl_target.h"
 # include  "svector.h"
 # include  "StringHeap.h"
@@ -181,21 +182,21 @@ class PBlock  : public PScope, public Statement {
 class PCallTask  : public Statement {
 
     public:
-      explicit PCallTask(const pform_name_t&n, const svector<PExpr*>&parms);
-      explicit PCallTask(perm_string n, const svector<PExpr*>&parms);
+      explicit PCallTask(const pform_name_t&n, const list<PExpr*>&parms);
+      explicit PCallTask(perm_string n, const list<PExpr*>&parms);
       ~PCallTask();
 
       const pform_name_t& path() const;
 
-      unsigned nparms() const { return parms_.count(); }
+      unsigned nparms() const { return parms_.size(); }
 
       PExpr*&parm(unsigned idx)
-	    { assert(idx < parms_.count());
+	    { assert(idx < parms_.size());
 	      return parms_[idx];
 	    }
 
       PExpr* parm(unsigned idx) const
-	    { assert(idx < parms_.count());
+	    { assert(idx < parms_.size());
 	      return parms_[idx];
 	    }
 
@@ -207,14 +208,14 @@ class PCallTask  : public Statement {
       NetProc* elaborate_usr(Design*des, NetScope*scope) const;
 
       pform_name_t path_;
-      svector<PExpr*> parms_;
+      vector<PExpr*> parms_;
 };
 
 class PCase  : public Statement {
 
     public:
       struct Item {
-	    svector<PExpr*>expr;
+	    list<PExpr*>expr;
 	    Statement*stat;
       };
 
diff --git a/elab_expr.cc b/elab_expr.cc
index 4a1e1385f..bb0f97392 100644
--- a/elab_expr.cc
+++ b/elab_expr.cc
@@ -1617,7 +1617,7 @@ unsigned PEConcat::test_width(Design*des, NetScope*scope,
       expr_type_ = IVL_VT_LOGIC;
 
       unsigned count_width = 0;
-      for (unsigned idx = 0 ; idx < parms_.count() ; idx += 1) {
+      for (unsigned idx = 0 ; idx < parms_.size() ; idx += 1) {
 	    tested_widths_[idx] = parms_[idx]->test_width(des, scope, 0, 0, expr_type__, unsized_flag);
 	    count_width += tested_widths_[idx];
       }
@@ -1730,10 +1730,10 @@ NetExpr* PEConcat::elaborate_expr(Design*des, NetScope*scope,
 
       unsigned wid_sum = 0;
       unsigned parm_cnt = 0;
-      svector<NetExpr*> parms(parms_.count());
+      svector<NetExpr*> parms(parms_.size());
 
 	/* Elaborate all the parameters and attach them to the concat node. */
-      for (unsigned idx = 0 ;  idx < parms_.count() ;  idx += 1) {
+      for (unsigned idx = 0 ;  idx < parms_.size() ;  idx += 1) {
 	    if (parms_[idx] == 0) {
 		  cerr << get_fileline() << ": error: Missing expression "
 		       << (idx+1) << " of concatenation list." << endl;
diff --git a/elab_lval.cc b/elab_lval.cc
index cb7bfd2fb..5ef8f8957 100644
--- a/elab_lval.cc
+++ b/elab_lval.cc
@@ -107,7 +107,7 @@ NetAssign_* PEConcat::elaborate_lval(Design*des,
 
       NetAssign_*res = 0;
 
-      for (unsigned idx = 0 ;  idx < parms_.count() ;  idx += 1) {
+      for (unsigned idx = 0 ;  idx < parms_.size() ;  idx += 1) {
 
 	    if (parms_[idx] == 0) {
 		  cerr << get_fileline() << ": error: Empty expressions "
diff --git a/elab_net.cc b/elab_net.cc
index a9cdb25fa..8442de6e7 100644
--- a/elab_net.cc
+++ b/elab_net.cc
@@ -41,7 +41,7 @@ NetNet* PEConcat::elaborate_lnet_common_(Design*des, NetScope*scope,
 {
       assert(scope);
 
-      svector<NetNet*>nets (parms_.count());
+      svector<NetNet*>nets (parms_.size());
       unsigned width = 0;
       unsigned errors = 0;
 
diff --git a/elab_pexpr.cc b/elab_pexpr.cc
index 1231119a7..228549650 100644
--- a/elab_pexpr.cc
+++ b/elab_pexpr.cc
@@ -144,14 +144,14 @@ NetEConcat* PEConcat::elaborate_pexpr(Design*des, NetScope*scope) const
       }
 
 	/* Make the empty concat expression. */
-      NetEConcat*tmp = new NetEConcat(parms_.count(), repeat);
+      NetEConcat*tmp = new NetEConcat(parms_.size(), repeat);
       tmp->set_line(*this);
 
 	/* Elaborate all the operands and attach them to the concat
 	   node. Use the elaborate_pexpr method instead of the
 	   elaborate_expr method. */
       bool fail = false;
-      for (unsigned idx = 0 ;  idx < parms_.count() ;  idx += 1) {
+      for (unsigned idx = 0 ;  idx < parms_.size() ;  idx += 1) {
 	    assert(parms_[idx]);
 	    NetExpr*ex = parms_[idx]->elaborate_pexpr(des, scope);
 	    if (ex == 0) continue;
diff --git a/elab_scope.cc b/elab_scope.cc
index 9814feabe..a805e3294 100644
--- a/elab_scope.cc
+++ b/elab_scope.cc
@@ -1321,17 +1321,17 @@ void PGModule::elaborate_scope_mod_instances_(Design*des, Module*mod, NetScope*s
 		  assert(parms_ == 0);
 		  list<perm_string>::const_iterator cur
 			= mod->param_names.begin();
-		  unsigned jdx = 0;
+		  list<PExpr*>::const_iterator jdx = overrides_->begin();
 		  for (;;) {
-			if (jdx >= overrides_->count())
+			if (jdx == overrides_->end())
 			      break;
 			if (cur == mod->param_names.end())
 			      break;
 
-			replace[*cur] = (*overrides_)[jdx];
+			replace[*cur] = *jdx;
 
-			jdx += 1;
-			cur ++;
+			++ jdx;
+			++ cur;
 		  }
 	    }
 
diff --git a/elab_sig.cc b/elab_sig.cc
index 3f393b045..98b97ddbb 100644
--- a/elab_sig.cc
+++ b/elab_sig.cc
@@ -468,15 +468,16 @@ void PFunction::elaborate_sig(Design*des, NetScope*scope) const
 	  case PTF_REG:
 	  case PTF_REG_S:
 	    if (return_type_.range) {
-		  probe_expr_width(des, scope, (*return_type_.range)[0]);
-		  probe_expr_width(des, scope, (*return_type_.range)[1]);
+		  ivl_assert(*this, return_type_.range->size() == 2);
+		  probe_expr_width(des, scope, return_type_.range->at(0));
+		  probe_expr_width(des, scope, return_type_.range->at(1));
 
 		  need_constant_expr = true;
 		  NetExpr*me = elab_and_eval(des, scope,
-					     (*return_type_.range)[0], -1);
+					     return_type_.range->at(0), -1);
 		  assert(me);
 		  NetExpr*le = elab_and_eval(des, scope,
-					     (*return_type_.range)[1], -1);
+					     return_type_.range->at(1), -1);
 		  assert(le);
 		  need_constant_expr = false;
 
diff --git a/elaborate.cc b/elaborate.cc
index 0815917c2..6e23f40a5 100644
--- a/elaborate.cc
+++ b/elaborate.cc
@@ -1105,7 +1105,7 @@ void PGModule::elaborate_mod_(Design*des, Module*rmod, NetScope*scope) const
 	// order of the declaration. If the source instantiation uses
 	// bind by order, this is the same as the source list. Otherwise,
 	// the source list is rearranged by name binding into this list.
-      svector<PExpr*>pins (rmod->port_count());
+      vector<PExpr*>pins (rmod->port_count());
 
 	// If the instance has a pins_ member, then we know we are
 	// binding by name. Therefore, make up a pins array that
@@ -1204,7 +1204,7 @@ void PGModule::elaborate_mod_(Design*des, Module*rmod, NetScope*scope) const
 	// to a concatenation, or connected to an internally
 	// unconnected port.
 
-      for (unsigned idx = 0 ;  idx < pins.count() ;  idx += 1) {
+      for (unsigned idx = 0 ;  idx < pins.size() ;  idx += 1) {
 
 	      // Skip unconnected module ports. This happens when a
 	      // null parameter is passed in.
@@ -1748,7 +1748,7 @@ void PGModule::elaborate_udp_(Design*des, PUdp*udp, NetScope*scope) const
 	   module or primitive, it interprets them as parameter
 	   overrides. Correct that misconception here. */
       if (overrides_) {
-	    if (overrides_->count() > 2) {
+	    if (overrides_->size() > 2) {
 		  cerr << get_fileline() << ": error: UDPs take at most two "
 		          "delay arguments." << endl;
 		  des->errors += 1;
@@ -1782,7 +1782,7 @@ void PGModule::elaborate_udp_(Design*des, PUdp*udp, NetScope*scope) const
 	// bind by order, this is the same as the source
 	// list. Otherwise, the source list is rearranged by name
 	// binding into this list.
-      svector<PExpr*>pins;
+      vector<PExpr*>pins;
 
 	// Detect binding by name. If I am binding by name, then make
 	// up a pins array that reflects the positions of the named
@@ -1790,7 +1790,7 @@ void PGModule::elaborate_udp_(Design*des, PUdp*udp, NetScope*scope) const
 	// place, then get the binding from the base class.
       if (pins_) {
 	    unsigned nexp = udp->ports.count();
-	    pins = svector<PExpr*>(nexp);
+	    pins = vector<PExpr*>(nexp);
 
 	      // Scan the bindings, matching them with port names.
 	    for (unsigned idx = 0 ;  idx < npins_ ;  idx += 1) {
@@ -2488,10 +2488,10 @@ NetProc* PCase::elaborate(Design*des, NetScope*scope) const
       for (unsigned idx = 0 ;  idx < items_->count() ;  idx += 1) {
 	    PCase::Item*cur = (*items_)[idx];
 
-	    if (cur->expr.count() == 0)
+	    if (cur->expr.empty())
 		  icount += 1;
 	    else
-		  icount += cur->expr.count();
+		  icount += cur->expr.size();
       }
 
       NetCase*res = new NetCase(type_, expr, icount);
@@ -2507,7 +2507,7 @@ NetProc* PCase::elaborate(Design*des, NetScope*scope) const
 	    assert(inum < icount);
 	    PCase::Item*cur = (*items_)[idx];
 
-	    if (cur->expr.count() == 0) {
+	    if (cur->expr.empty()) {
 		    /* If there are no expressions, then this is the
 		       default case. */
 		  NetProc*st = 0;
@@ -2517,17 +2517,19 @@ NetProc* PCase::elaborate(Design*des, NetScope*scope) const
 		  res->set_case(inum, 0, st);
 		  inum += 1;
 
-	    } else for (unsigned e = 0; e < cur->expr.count(); e += 1) {
+	    } else for (list<PExpr*>::iterator idx_expr = cur->expr.begin()
+			      ; idx_expr != cur->expr.end() ; ++idx_expr) {
 
 		    /* If there are one or more expressions, then
 		       iterate over the guard expressions, elaborating
 		       a separate case for each. (Yes, the statement
 		       will be elaborated again for each.) */
+		  PExpr*cur_expr = *idx_expr;
 		  NetExpr*gu = 0;
 		  NetProc*st = 0;
-		  assert(cur->expr[e]);
-		  probe_expr_width(des, scope, cur->expr[e]);
-		  gu = elab_and_eval(des, scope, cur->expr[e], -1);
+		  assert(cur_expr);
+		  probe_expr_width(des, scope, cur_expr);
+		  gu = elab_and_eval(des, scope, cur_expr, -1);
 
 		  if (cur->stat)
 			st = cur->stat->elaborate(des, scope);
diff --git a/eval.cc b/eval.cc
index 1bf506552..84dbc5aea 100644
--- a/eval.cc
+++ b/eval.cc
@@ -147,7 +147,7 @@ verinum* PEConcat::eval_const(Design*des, NetScope*scope) const
       if (accum == 0)
 	    return 0;
 
-      for (unsigned idx = 1 ;  idx < parms_.count() ;  idx += 1) {
+      for (unsigned idx = 1 ;  idx < parms_.size() ;  idx += 1) {
 
 	    verinum*tmp = parms_[idx]->eval_const(des, scope);
 	    if (tmp == 0) {
diff --git a/parse.y b/parse.y
index 298e824b6..35b105aa4 100644
--- a/parse.y
+++ b/parse.y
@@ -38,7 +38,7 @@ extern void lex_end_table();
 bool have_timeunit_decl = false;
 bool have_timeprec_decl = false;
 
-static svector<PExpr*>* param_active_range = 0;
+static list<PExpr*>* param_active_range = 0;
 static bool param_active_signed = false;
 static ivl_variable_type_t param_active_type = IVL_VT_LOGIC;
 
@@ -48,7 +48,7 @@ static struct {
       NetNet::PortType port_type;
       ivl_variable_type_t var_type;
       bool sign_flag;
-      svector<PExpr*>* range;
+      list<PExpr*>* range;
 } port_declaration_context = {NetNet::NONE, NetNet::NOT_A_PORT,
                               IVL_VT_NO_TYPE, false, 0};
 
@@ -106,16 +106,41 @@ static list<pair<perm_string,PExpr*> >* make_port_list(list<pair<perm_string,
       return tmp;
 }
 
-static svector<PExpr*>* make_range_from_width(uint64_t wid)
+static list<PExpr*>* make_range_from_width(uint64_t wid)
 {
-      svector<PExpr*>*range = new svector<PExpr*>(2);
+      list<PExpr*>*range = new list<PExpr*>;
 
-      (*range)[0] = new PENumber(new verinum(wid-1, integer_width));
-      (*range)[1] = new PENumber(new verinum((uint64_t)0, integer_width));
+      range->push_back(new PENumber(new verinum(wid-1, integer_width)));
+      range->push_back(new PENumber(new verinum((uint64_t)0, integer_width)));
 
       return range;
 }
 
+/*
+ * Make a rqange vector from an existing pair of expressions.
+ */
+static vector<PExpr*>* make_range_vector(list<PExpr*>*that)
+{
+      assert(that->size() == 2);
+      vector<PExpr*>*tmp = new vector<PExpr*> (2);
+      tmp->at(0) = that->front();
+      tmp->at(1) = that->back();
+      delete that;
+      return tmp;
+}
+
+/*
+ * Make a range vector from a width. Generate the msb and lsb
+ * expressions to get the canonical range for the given width.
+ */
+static vector<PExpr*>* make_range_vector(uint64_t wid)
+{
+      vector<PExpr*>*tmp = new vector<PExpr*> (2);
+      tmp->at(0) = new PENumber(new verinum(wid-1, integer_width));
+      tmp->at(1) = new PENumber(new verinum((uint64_t)0, integer_width));
+      return tmp;
+}
+
 static list<perm_string>* list_from_identifier(char*id)
 {
       list<perm_string>*tmp = new list<perm_string>;
@@ -131,15 +156,12 @@ static list<perm_string>* list_from_identifier(list<perm_string>*tmp, char*id)
       return tmp;
 }
 
-static svector<PExpr*>* copy_range(svector<PExpr*>* orig)
+static list<PExpr*>* copy_range(list<PExpr*>* orig)
 {
-      svector<PExpr*>*copy = 0;
+      list<PExpr*>*copy = 0;
 
-      if (orig) {
-	    copy = new svector<PExpr*>(2);
-	    (*copy)[0] = (*orig)[0];
-	    (*copy)[1] = (*orig)[1];
-      }
+      if (orig)
+	    copy = new list<PExpr*> (*orig);
 
       return copy;
 }
@@ -156,7 +178,7 @@ template <class T> void append(vector<T>&out, const vector<T>&in)
  */
 static PECallFunction*make_call_function(perm_string tn, PExpr*arg)
 {
-      svector<PExpr*> parms(1);
+      vector<PExpr*> parms(1);
       parms[0] = arg;
       PECallFunction*tmp = new PECallFunction(tn, parms);
       return tmp;
@@ -164,7 +186,7 @@ static PECallFunction*make_call_function(perm_string tn, PExpr*arg)
 
 static PECallFunction*make_call_function(perm_string tn, PExpr*arg1, PExpr*arg2)
 {
-      svector<PExpr*> parms(2);
+      vector<PExpr*> parms(2);
       parms[0] = arg1;
       parms[1] = arg2;
       PECallFunction*tmp = new PECallFunction(tn, parms);
@@ -229,7 +251,7 @@ static named_number_t* make_named_number(perm_string name, const verinum&val)
       struct parmvalue_t*parmvalue;
 
       PExpr*expr;
-      svector<PExpr*>*exprs;
+      list<PExpr*>*exprs;
 
       svector<PEEvent*>*event_expr;
 
@@ -769,39 +791,39 @@ defparam_assign_list
 
 delay1
 	: '#' delay_value_simple
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $2;
+		{ list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($2);
 		  $$ = tmp;
 		}
 	| '#' '(' delay_value ')'
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $3;
+		{ list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($3);
 		  $$ = tmp;
 		}
 	;
 
 delay3
 	: '#' delay_value_simple
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $2;
+		{ list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($2);
 		  $$ = tmp;
 		}
 	| '#' '(' delay_value ')'
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $3;
+		{ list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($3);
 		  $$ = tmp;
 		}
 	| '#' '(' delay_value ',' delay_value ')'
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(2);
-		  (*tmp)[0] = $3;
-		  (*tmp)[1] = $5;
+		{ list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($3);
+		  tmp->push_back($5);
 		  $$ = tmp;
 		}
 	| '#' '(' delay_value ',' delay_value ',' delay_value ')'
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(3);
-		  (*tmp)[0] = $3;
-		  (*tmp)[1] = $5;
-		  (*tmp)[2] = $7;
+		{ list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($3);
+		  tmp->push_back($5);
+		  tmp->push_back($7);
 		  $$ = tmp;
 		}
 	;
@@ -812,17 +834,17 @@ delay3_opt
 	;
 
 delay_value_list
-        : delay_value
-              { svector<PExpr*>*tmp = new svector<PExpr*>(1);
-	        (*tmp)[0] = $1;
-		$$ = tmp;
-	      }
-	| delay_value_list ',' delay_value
-              { svector<PExpr*>*tmp = new svector<PExpr*>(*$1, $3);
-		delete $1;
-		$$ = tmp;
-	      }
-	;
+  : delay_value
+      { list<PExpr*>*tmp = new list<PExpr*>;
+	tmp->push_back($1);
+	$$ = tmp;
+      }
+  | delay_value_list ',' delay_value
+      { list<PExpr*>*tmp = $1;
+	tmp->push_back($3);
+	$$ = tmp;
+      }
+  ;
 
 delay_value
 	: expression
@@ -1360,41 +1382,40 @@ expr_mintypmax
      expression list, so can be used where nul expressions are not allowed. */
 
 expression_list_with_nuls
-	: expression_list_with_nuls ',' expression
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(*$1, $3);
-		  delete $1;
-		  $$ = tmp;
-		}
-	| expression
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $1;
-		  $$ = tmp;
-		}
-	|
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = 0;
-		  $$ = tmp;
-		}
-
-	| expression_list_with_nuls ','
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(*$1, 0);
-		  delete $1;
-		  $$ = tmp;
-		}
+  : expression_list_with_nuls ',' expression
+      { list<PExpr*>*tmp = $1;
+	tmp->push_back($3);
+	$$ = tmp;
+      }
+  | expression
+      { list<PExpr*>*tmp = new list<PExpr*>;
+	tmp->push_back($1);
+	$$ = tmp;
+      }
+  |
+      { list<PExpr*>*tmp = new list<PExpr*>;
+        tmp->push_back(0);
+	$$ = tmp;
+      }
+  | expression_list_with_nuls ','
+      { list<PExpr*>*tmp = $1;
+	tmp->push_back(0);
+	$$ = tmp;
+      }
 	;
 
 expression_list_proper
-	: expression_list_proper ',' expression
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(*$1, $3);
-		  delete $1;
-		  $$ = tmp;
-		}
-	| expression
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $1;
-		  $$ = tmp;
-		}
-        ;
+  : expression_list_proper ',' expression
+      { list<PExpr*>*tmp = $1;
+        tmp->push_back($3);
+        $$ = tmp;
+      }
+  | expression
+      { list<PExpr*>*tmp = new list<PExpr*>;
+	tmp->push_back($1);
+	$$ = tmp;
+      }
+  ;
 
 expr_primary
 	: number
@@ -1695,11 +1716,12 @@ gate_instance
 
 	| IDENTIFIER range '(' expression_list_with_nuls ')'
 		{ lgate*tmp = new lgate;
-		  svector<PExpr*>*rng = $2;
+		  list<PExpr*>*rng = $2;
 		  tmp->name = $1;
 		  tmp->parms = $4;
-		  tmp->range[0] = (*rng)[0];
-		  tmp->range[1] = (*rng)[1];
+		  tmp->range[0] = rng->front(); rng->pop_front();
+		  tmp->range[1] = rng->front(); rng->pop_front();
+		  assert(rng->empty());
 		  tmp->file  = @1.text;
 		  tmp->lineno = @1.first_line;
 		  delete[]$1;
@@ -1719,12 +1741,13 @@ gate_instance
 
 	| IDENTIFIER range
 		{ lgate*tmp = new lgate;
-		  svector<PExpr*>*rng = $2;
+		  list<PExpr*>*rng = $2;
 		  tmp->name = $1;
 		  tmp->parms = 0;
 		  tmp->parms_by_name = 0;
-		  tmp->range[0] = (*rng)[0];
-		  tmp->range[1] = (*rng)[1];
+		  tmp->range[0] = rng->front(); rng->pop_front();
+		  tmp->range[1] = rng->front(); rng->pop_front();
+		  assert(rng->empty());
 		  tmp->file  = @1.text;
 		  tmp->lineno = @1.first_line;
 		  delete[]$1;
@@ -1747,12 +1770,13 @@ gate_instance
 
 	| IDENTIFIER range '(' port_name_list ')'
 		{ lgate*tmp = new lgate;
-		  svector<PExpr*>*rng = $2;
+		  list<PExpr*>*rng = $2;
 		  tmp->name = $1;
 		  tmp->parms = 0;
 		  tmp->parms_by_name = $4;
-		  tmp->range[0] = (*rng)[0];
-		  tmp->range[1] = (*rng)[1];
+		  tmp->range[0] = rng->front(); rng->pop_front();
+		  tmp->range[1] = rng->front(); rng->pop_front();
+		  assert(rng->empty());
 		  tmp->file  = @1.text;
 		  tmp->lineno = @1.first_line;
 		  delete[]$1;
@@ -2011,7 +2035,7 @@ port_declaration
   | attribute_list_opt K_input atom2_type signed_unsigned_opt IDENTIFIER
       { Module::port_t*ptmp;
 	perm_string name = lex_strings.make($5);
-	svector<PExpr*>*use_range = make_range_from_width($3);
+	list<PExpr*>*use_range = make_range_from_width($3);
 	ptmp = pform_module_port_reference(name, @2.text,
 					   @2.first_line);
 	pform_module_define_port(@2, name, NetNet::PINPUT,
@@ -2105,7 +2129,7 @@ port_declaration
   | attribute_list_opt K_output atom2_type signed_unsigned_opt IDENTIFIER
       { Module::port_t*ptmp;
 	perm_string name = lex_strings.make($5);
-	svector<PExpr*>*use_range = make_range_from_width($3);
+	list<PExpr*>*use_range = make_range_from_width($3);
 	ptmp = pform_module_port_reference(name, @2.text,
 					   @2.first_line);
 	pform_module_define_port(@2, name, NetNet::POUTPUT,
@@ -2186,24 +2210,24 @@ lpvalue
   /* Continuous assignments have a list of individual assignments. */
 
 cont_assign
-	: lpvalue '=' expression
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(2);
-		  (*tmp)[0] = $1;
-		  (*tmp)[1] = $3;
-		  $$ = tmp;
-		}
-	;
+  : lpvalue '=' expression
+      { list<PExpr*>*tmp = new list<PExpr*>;
+	tmp->push_back($1);
+	tmp->push_back($3);
+	$$ = tmp;
+      }
+  ;
 
 cont_assign_list
-	: cont_assign_list ',' cont_assign
-		{ svector<PExpr*>*tmp = new svector<PExpr*>(*$1, *$3);
-		  delete $1;
-		  delete $3;
-		  $$ = tmp;
-		}
-	| cont_assign
-		{ $$ = $1; }
-	;
+  : cont_assign_list ',' cont_assign
+      { list<PExpr*>*tmp = $1;
+	tmp->splice(tmp->end(), *$3);
+	delete $3;
+	$$ = tmp;
+      }
+  | cont_assign
+      { $$ = $1; }
+  ;
 
   /* We allow zero, one or two unique declarations. */
 local_timeunit_prec_decl_opt
@@ -2876,14 +2900,7 @@ parameter_assign_decl
 	param_active_type = IVL_VT_LOGIC;
       }
   | K_integer
-      { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-        PExpr*re;
-        re = new PENumber(new verinum(integer_width-1, integer_width));
-        (*range_stub)[0] = re;
-        re = new PENumber(new verinum((uint64_t)0, integer_width));
-        (*range_stub)[1] = re;
-        /* The default range is [31:0] */
-        param_active_range = range_stub;
+      { param_active_range = make_range_from_width(integer_width);
 	param_active_signed = true;
 	param_active_type = IVL_VT_LOGIC;
       }
@@ -2893,14 +2910,7 @@ parameter_assign_decl
 	param_active_type = IVL_VT_LOGIC;
       }
   | K_time
-      { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-        PExpr*re;
-        re = new PENumber(new verinum((uint64_t)63, integer_width));
-        (*range_stub)[0] = re;
-        re = new PENumber(new verinum((uint64_t)0, integer_width));
-        (*range_stub)[1] = re;
-        /* The range is [63:0] */
-        param_active_range = range_stub;
+      { param_active_range = make_range_from_width(64);
 	param_active_signed = false;
 	param_active_type = IVL_VT_LOGIC;
       }
@@ -3005,14 +3015,7 @@ localparam_assign_decl
 	param_active_type = IVL_VT_LOGIC;
       }
   | K_integer
-      { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-        PExpr*re;
-        re = new PENumber(new verinum(integer_width-1, integer_width));
-        (*range_stub)[0] = re;
-        re = new PENumber(new verinum((uint64_t)0, integer_width));
-        (*range_stub)[1] = re;
-        /* The default range is [31:0] */
-        param_active_range = range_stub;
+      { param_active_range = make_range_from_width(integer_width);
 	param_active_signed = true;
 	param_active_type = IVL_VT_LOGIC;
       }
@@ -3022,14 +3025,7 @@ localparam_assign_decl
 	param_active_type = IVL_VT_LOGIC;
       }
   | K_time
-      { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-        PExpr*re;
-        re = new PENumber(new verinum((uint64_t)63, integer_width));
-        (*range_stub)[0] = re;
-        re = new PENumber(new verinum((uint64_t)0, integer_width));
-        (*range_stub)[1] = re;
-        /* The range is [63:0] */
-        param_active_range = range_stub;
+      { param_active_range = make_range_from_width(64);
 	param_active_signed = false;
 	param_active_type = IVL_VT_LOGIC;
       }
@@ -3090,8 +3086,8 @@ parameter_value_opt
 		  FILE_NAME(tmp, @1);
 
 		  struct parmvalue_t*lst = new struct parmvalue_t;
-		  lst->by_order = new svector<PExpr*>(1);
-		  (*lst->by_order)[0] = tmp;
+		  lst->by_order = new list<PExpr*>;
+		  lst->by_order->push_back(tmp);
 		  lst->by_name = 0;
 		  $$ = lst;
 		  based_size = 0;
@@ -3340,13 +3336,13 @@ port_type
 	;
 
 range
-	: '[' expression ':' expression ']'
-		{ svector<PExpr*>*tmp = new svector<PExpr*> (2);
-		  (*tmp)[0] = $2;
-		  (*tmp)[1] = $4;
-		  $$ = tmp;
-		}
-	;
+  : '[' expression ':' expression ']'
+      { list<PExpr*>*tmp = new list<PExpr*>;
+	tmp->push_back($2);
+	tmp->push_back($4);
+	$$ = tmp;
+      }
+  ;
 
 range_opt
 	: range
@@ -3376,16 +3372,16 @@ dimensions
 
   /* This is used to express the return type of a function. */
 function_range_or_type_opt
-  : range            { $$.range = $1; $$.type = PTF_REG; }
-  | K_signed range   { $$.range = $2; $$.type = PTF_REG_S; }
-  | K_unsigned range { $$.range = $2; $$.type = PTF_REG; }
+  : range            { $$.range = make_range_vector($1); $$.type = PTF_REG; }
+  | K_signed range   { $$.range = make_range_vector($2); $$.type = PTF_REG_S; }
+  | K_unsigned range { $$.range = make_range_vector($2); $$.type = PTF_REG; }
   | K_integer  { $$.range = 0;  $$.type = PTF_INTEGER; }
   | K_real     { $$.range = 0;  $$.type = PTF_REAL; }
   | K_realtime { $$.range = 0;  $$.type = PTF_REALTIME; }
   | K_time     { $$.range = 0;  $$.type = PTF_TIME; }
-  | atom2_type { $$.range = make_range_from_width($1); $$.type = PTF_ATOM2_S; }
-  | atom2_type K_signed  { $$.range = make_range_from_width($1); $$.type = PTF_ATOM2_S; }
-  | atom2_type K_unsigned { $$.range = make_range_from_width($1); $$.type = PTF_ATOM2; }
+  | atom2_type { $$.range = make_range_vector($1); $$.type = PTF_ATOM2_S; }
+  | atom2_type K_signed  { $$.range = make_range_vector($1); $$.type = PTF_ATOM2_S; }
+  | atom2_type K_unsigned { $$.range = make_range_vector($1); $$.type = PTF_ATOM2; }
   |            { $$.range = 0;  $$.type = PTF_REG; }
   ;
 
@@ -3619,8 +3615,8 @@ specify_edge_path_decl
 	: specify_edge_path '=' '(' delay_value_list ')'
                 { $$ = pform_assign_path_delay($1, $4); }
 	| specify_edge_path '=' delay_value_simple
-                { svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $3;
+                { list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($3);
 		  $$ = pform_assign_path_delay($1, tmp);
 		}
 	;
@@ -3656,8 +3652,8 @@ specify_simple_path_decl
 	: specify_simple_path '=' '(' delay_value_list ')'
                 { $$ = pform_assign_path_delay($1, $4); }
 	| specify_simple_path '=' delay_value_simple
-                { svector<PExpr*>*tmp = new svector<PExpr*>(1);
-		  (*tmp)[0] = $3;
+                { list<PExpr*>*tmp = new list<PExpr*>;
+		  tmp->push_back($3);
 		  $$ = pform_assign_path_delay($1, tmp);
 		}
 	| specify_simple_path '=' '(' error ')'
@@ -4044,8 +4040,9 @@ statement
 		  yyerror(@1, "error: Error in while loop condition.");
 		}
 	| delay1 statement_or_null
-		{ PExpr*del = (*$1)[0];
-		  assert($1->count() == 1);
+                { PExpr*del = $1->front();
+		  assert($1->size() == 1);
+		  delete $1;
 		  PDelayStatement*tmp = new PDelayStatement(del, $2);
 		  FILE_NAME(tmp, @1);
 		  $$ = tmp;
@@ -4096,15 +4093,15 @@ statement
 		  $$ = new PNoop;
 		}
 	| lpvalue '=' delay1 expression ';'
-		{ assert($3->count() == 1);
-		  PExpr*del = (*$3)[0];
+		{ PExpr*del = $3->front(); $3->pop_front();
+		  assert($3->empty());
 		  PAssign*tmp = new PAssign($1,del,$4);
 		  FILE_NAME(tmp, @1);
 		  $$ = tmp;
 		}
 	| lpvalue K_LE delay1 expression ';'
-		{ assert($3->count() == 1);
-		  PExpr*del = (*$3)[0];
+		{ PExpr*del = $3->front(); $3->pop_front();
+		  assert($3->empty());
 		  PAssignNB*tmp = new PAssignNB($1,del,$4);
 		  FILE_NAME(tmp, @1);
 		  $$ = tmp;
@@ -4146,7 +4143,7 @@ statement
 		  $$ = tmp;
 		}
 	| SYSTEM_IDENTIFIER ';'
-		{ svector<PExpr*>pt (0);
+		{ list<PExpr*>pt;
 		  PCallTask*tmp = new PCallTask(lex_strings.make($1), pt);
 		  FILE_NAME(tmp,@1);
 		  delete[]$1;
@@ -4165,14 +4162,14 @@ statement
      want it. So accept it explicitly. */
 
 	| hierarchy_identifier '(' ')' ';'
-		{ svector<PExpr*>pt (0);
+		{ list<PExpr*>pt;
 		  PCallTask*tmp = new PCallTask(*$1, pt);
 		  FILE_NAME(tmp, @1);
 		  delete $1;
 		  $$ = tmp;
 		}
 	| hierarchy_identifier ';'
-		{ svector<PExpr*>pt (0);
+		{ list<PExpr*>pt;
 		  PCallTask*tmp = new PCallTask(*$1, pt);
 		  FILE_NAME(tmp, @1);
 		  delete $1;
@@ -4249,96 +4246,57 @@ task_port_item
   /* When the port is an integer, infer a signed vector of the integer
      shape. Generate a range ([31:0]) to make it work. */
 
-	| K_input K_integer list_of_identifiers ';'
-                { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum(integer_width-1,
-						integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::PINPUT,
+  | K_input K_integer list_of_identifiers ';'
+      { list<PExpr*>*range_stub = make_range_from_width(integer_width);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::PINPUT,
 						IVL_VT_LOGIC, true,
 						range_stub, $3,
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
-	| K_output K_integer list_of_identifiers ';'
-		{ svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum(integer_width-1,
-						integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::POUTPUT,
+	$$ = tmp;
+      }
+  | K_output K_integer list_of_identifiers ';'
+      { list<PExpr*>*range_stub = make_range_from_width(integer_width);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::POUTPUT,
 						IVL_VT_LOGIC, true,
 						range_stub, $3,
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
-	| K_inout K_integer list_of_identifiers ';'
-		{ svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum(integer_width-1,
-						integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::PINOUT,
+	$$ = tmp;
+      }
+  | K_inout K_integer list_of_identifiers ';'
+      { list<PExpr*>*range_stub = make_range_from_width(integer_width);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::PINOUT,
 						IVL_VT_LOGIC, true,
 						range_stub, $3,
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
+	$$ = tmp;
+      }
 
   /* Ports can be time with a width of [63:0] (unsigned). */
 
-	| K_input K_time list_of_identifiers ';'
-                { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum((uint64_t)63, integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::PINPUT,
+  | K_input K_time list_of_identifiers ';'
+      { list<PExpr*>*range_stub = make_range_from_width(64);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::PINPUT,
 						IVL_VT_LOGIC, false,
 						range_stub, $3,
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
-	| K_output K_time list_of_identifiers ';'
-		{ svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum((uint64_t)63, integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::POUTPUT,
+	$$ = tmp;
+      }
+  | K_output K_time list_of_identifiers ';'
+      { list<PExpr*>*range_stub = make_range_from_width(64);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::POUTPUT,
 						IVL_VT_LOGIC, false,
 						range_stub, $3,
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
-	| K_inout K_time list_of_identifiers ';'
-		{ svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum((uint64_t)63, integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::PINOUT,
+	$$ = tmp;
+      }
+  | K_inout K_time list_of_identifiers ';'
+      { list<PExpr*>*range_stub = make_range_from_width(64);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::PINOUT,
 						IVL_VT_LOGIC, false,
 						range_stub, $3,
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
+	$$ = tmp;
+      }
 
   /* Ports can be real or realtime. */
 
@@ -4431,74 +4389,53 @@ task_port_decl
 
   /* Ports can be integer with a width of [31:0]. */
 
-	| K_input K_integer IDENTIFIER
-                { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum(integer_width-1,
-						integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  port_declaration_context.port_type = NetNet::PINPUT;
-		  port_declaration_context.var_type = IVL_VT_LOGIC;
-		  port_declaration_context.sign_flag = true;
-		  delete port_declaration_context.range;
-		  port_declaration_context.range = copy_range(range_stub);
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::PINPUT,
+  | K_input K_integer IDENTIFIER
+      { list<PExpr*>*range_stub = make_range_from_width(integer_width);
+	port_declaration_context.port_type = NetNet::PINPUT;
+	port_declaration_context.var_type = IVL_VT_LOGIC;
+	port_declaration_context.sign_flag = true;
+	delete port_declaration_context.range;
+	port_declaration_context.range = copy_range(range_stub);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::PINPUT,
 						IVL_VT_LOGIC, true,
 						range_stub,
 						list_from_identifier($3),
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
-	| K_output K_integer IDENTIFIER
-                { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum(integer_width-1,
-						integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  port_declaration_context.port_type = NetNet::POUTPUT;
-		  port_declaration_context.var_type = IVL_VT_LOGIC;
-		  port_declaration_context.sign_flag = true;
-		  delete port_declaration_context.range;
-		  port_declaration_context.range = copy_range(range_stub);
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::POUTPUT,
+	$$ = tmp;
+      }
+  | K_output K_integer IDENTIFIER
+      { list<PExpr*>*range_stub = make_range_from_width(integer_width);
+	port_declaration_context.port_type = NetNet::POUTPUT;
+	port_declaration_context.var_type = IVL_VT_LOGIC;
+	port_declaration_context.sign_flag = true;
+	delete port_declaration_context.range;
+	port_declaration_context.range = copy_range(range_stub);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::POUTPUT,
 						IVL_VT_LOGIC, true,
 						range_stub,
 						list_from_identifier($3),
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
-	| K_inout K_integer IDENTIFIER
-                { svector<PExpr*>*range_stub = new svector<PExpr*>(2);
-		  PExpr*re;
-		  re = new PENumber(new verinum(integer_width-1,
-						integer_width));
-		  (*range_stub)[0] = re;
-		  re = new PENumber(new verinum((uint64_t)0, integer_width));
-		  (*range_stub)[1] = re;
-		  port_declaration_context.port_type = NetNet::PINOUT;
-		  port_declaration_context.var_type = IVL_VT_LOGIC;
-		  port_declaration_context.sign_flag = true;
-		  delete port_declaration_context.range;
-		  port_declaration_context.range = copy_range(range_stub);
-		  svector<PWire*>*tmp
-			= pform_make_task_ports(NetNet::PINOUT,
+	$$ = tmp;
+      }
+  | K_inout K_integer IDENTIFIER
+      { list<PExpr*>*range_stub = make_range_from_width(integer_width);
+	port_declaration_context.port_type = NetNet::PINOUT;
+	port_declaration_context.var_type = IVL_VT_LOGIC;
+	port_declaration_context.sign_flag = true;
+	delete port_declaration_context.range;
+	port_declaration_context.range = copy_range(range_stub);
+	svector<PWire*>*tmp = pform_make_task_ports(NetNet::PINOUT,
 						IVL_VT_LOGIC, true,
 						range_stub,
 						list_from_identifier($3),
 						@1.text, @1.first_line);
-		  $$ = tmp;
-		}
+	$$ = tmp;
+      }
 
   /* Ports can be time with a width of [63:0] (unsigned). */
 
   | K_input K_time IDENTIFIER
-     { svector<PExpr*>*range_stub = make_range_from_width(64);
+     { list<PExpr*>*range_stub = make_range_from_width(64);
        port_declaration_context.port_type = NetNet::PINPUT;
        port_declaration_context.var_type = IVL_VT_LOGIC;
        port_declaration_context.sign_flag = false;
@@ -4512,7 +4449,7 @@ task_port_decl
        $$ = tmp;
      }
   | K_output K_time IDENTIFIER
-     { svector<PExpr*>*range_stub = make_range_from_width(64);
+     { list<PExpr*>*range_stub = make_range_from_width(64);
        port_declaration_context.port_type = NetNet::POUTPUT;
        port_declaration_context.var_type = IVL_VT_LOGIC;
        port_declaration_context.sign_flag = false;
@@ -4526,7 +4463,7 @@ task_port_decl
        $$ = tmp;
      }
   | K_inout K_time IDENTIFIER
-     { svector<PExpr*>*range_stub = make_range_from_width(64);
+     { list<PExpr*>*range_stub = make_range_from_width(64);
        port_declaration_context.port_type = NetNet::PINOUT;
        port_declaration_context.var_type = IVL_VT_LOGIC;
        port_declaration_context.sign_flag = false;
@@ -4585,7 +4522,7 @@ task_port_decl
   /* Ports can be 2-value atom types. */
 
   | K_input atom2_type signed_unsigned_opt IDENTIFIER
-     { svector<PExpr*>*range_stub = make_range_from_width($2);
+     { list<PExpr*>*range_stub = make_range_from_width($2);
        port_declaration_context.port_type = NetNet::PINPUT;
        port_declaration_context.var_type = IVL_VT_BOOL;
        port_declaration_context.sign_flag = $3;
@@ -4599,21 +4536,21 @@ task_port_decl
      }
 
   | K_output atom2_type signed_unsigned_opt IDENTIFIER
-     { svector<PExpr*>*range_stub = make_range_from_width($2);
+     { list<PExpr*>*range_stub = make_range_from_width($2);
        port_declaration_context.port_type = NetNet::POUTPUT;
        port_declaration_context.var_type = IVL_VT_BOOL;
        port_declaration_context.sign_flag = $3;
        delete port_declaration_context.range;
        port_declaration_context.range = copy_range(range_stub);
        svector<PWire*>*tmp = pform_make_task_ports(NetNet::POUTPUT,
-						   IVL_VT_BOOL, $3,
-						   range_stub, list_from_identifier($4),
-						   @1.text, @1.first_line);
+					   IVL_VT_BOOL, $3,
+					   range_stub, list_from_identifier($4),
+					   @1.text, @1.first_line);
        $$ = tmp;
      }
 
   | K_inout atom2_type signed_unsigned_opt IDENTIFIER
-     { svector<PExpr*>*range_stub = make_range_from_width($2);
+     { list<PExpr*>*range_stub = make_range_from_width($2);
        port_declaration_context.port_type = NetNet::PINOUT;
        port_declaration_context.var_type = IVL_VT_BOOL;
        port_declaration_context.sign_flag = $3;
diff --git a/pform.cc b/pform.cc
index 010e8d260..953cd3a07 100644
--- a/pform.cc
+++ b/pform.cc
@@ -939,7 +939,7 @@ void pform_start_generate_nblock(const struct vlltype&li, char*name)
  * case schema can only instantiate exactly one item, so the items
  * need not have a unique number.
  */
-void pform_generate_case_item(const struct vlltype&li, svector<PExpr*>*expr_list)
+void pform_generate_case_item(const struct vlltype&li, list<PExpr*>*expr_list)
 {
       assert(pform_cur_generate);
       assert(pform_cur_generate->scheme_type == PGenerate::GS_CASE);
@@ -958,9 +958,13 @@ void pform_generate_case_item(const struct vlltype&li, svector<PExpr*>*expr_list
       pform_cur_generate->loop_step = 0;
 
       if (expr_list != 0) {
-	    pform_cur_generate->item_test.resize(expr_list->count());
-	    for (unsigned idx = 0 ; idx < expr_list->count() ; idx += 1)
-		  pform_cur_generate->item_test[idx] = expr_list[0][idx];
+	    list<PExpr*>::iterator expr_cur = expr_list->begin();
+	    pform_cur_generate->item_test.resize(expr_list->size());
+	    for (unsigned idx = 0 ; idx < expr_list->size() ; idx += 1) {
+		  pform_cur_generate->item_test[idx] = *expr_cur;
+		  ++ expr_cur;
+	    }
+	    assert(expr_cur == expr_list->end());
       }
 }
 
@@ -1398,7 +1402,7 @@ void pform_make_udp(perm_string name, bool synchronous_flag,
  * and the name that I receive only has the tail component.
  */
 static void pform_set_net_range(perm_string name,
-				const svector<PExpr*>*range,
+				const list<PExpr*>*range,
 				bool signed_flag,
 				ivl_variable_type_t dt,
 				PWSRType rt)
@@ -1415,10 +1419,8 @@ static void pform_set_net_range(perm_string name,
 	    cur->set_range(0, 0, rt, true);
 
       } else {
-	    assert(range->count() == 2);
-	    assert((*range)[0]);
-	    assert((*range)[1]);
-	    cur->set_range((*range)[0], (*range)[1], rt, false);
+	    assert(range->size() == 2);
+	    cur->set_range(range->front(), range->back(), rt, false);
       }
       cur->set_signed(signed_flag);
 
@@ -1427,12 +1429,12 @@ static void pform_set_net_range(perm_string name,
 }
 
 void pform_set_net_range(list<perm_string>*names,
-			 svector<PExpr*>*range,
+			 list<PExpr*>*range,
 			 bool signed_flag,
 			 ivl_variable_type_t dt,
 			 PWSRType rt)
 {
-      assert((range == 0) || (range->count() == 2));
+      assert((range == 0) || (range->size() == 2));
 
       for (list<perm_string>::iterator cur = names->begin()
 		 ; cur != names->end()
@@ -1484,7 +1486,7 @@ void pform_make_events(list<perm_string>*names, const char*fn, unsigned ln)
  */
 void pform_makegate(PGBuiltin::Type type,
 		    struct str_pair_t str,
-		    svector<PExpr*>* delay,
+		    list<PExpr*>* delay,
 		    const lgate&info,
 		    svector<named_pexpr_t*>*attr)
 {
@@ -1495,8 +1497,9 @@ void pform_makegate(PGBuiltin::Type type,
 	    return;
       }
 
-      for (unsigned idx = 0 ;  idx < info.parms->count() ;  idx += 1) {
-            pform_declare_implicit_nets((*info.parms)[idx]);
+      for (list<PExpr*>::iterator cur = info.parms->begin()
+		 ; cur != info.parms->end() ; ++cur) {
+	    pform_declare_implicit_nets(*cur);
       }
 
       perm_string dev_name = lex_strings.make(info.name);
@@ -1523,7 +1526,7 @@ void pform_makegate(PGBuiltin::Type type,
 
 void pform_makegates(PGBuiltin::Type type,
 		     struct str_pair_t str,
-		     svector<PExpr*>*delay,
+		     list<PExpr*>*delay,
 		     svector<lgate>*gates,
 		     svector<named_pexpr_t*>*attr)
 {
@@ -1559,12 +1562,13 @@ void pform_makegates(PGBuiltin::Type type,
 static void pform_make_modgate(perm_string type,
 			       perm_string name,
 			       struct parmvalue_t*overrides,
-			       svector<PExpr*>*wires,
+			       list<PExpr*>*wires,
 			       PExpr*msb, PExpr*lsb,
 			       const char*fn, unsigned ln)
 {
-      for (unsigned idx = 0 ;  idx < wires->count() ;  idx += 1) {
-            pform_declare_implicit_nets((*wires)[idx]);
+      for (list<PExpr*>::iterator idx = wires->begin()
+		 ; idx != wires->end() ; ++idx) {
+	    pform_declare_implicit_nets(*idx);
       }
 
       PGModule*cur = new PGModule(type, name, wires);
@@ -1657,9 +1661,9 @@ void pform_make_modgates(perm_string type,
 		    /* If there are no parameters, the parser will be
 		       tricked into thinking it is one empty
 		       parameter. This fixes that. */
-		  if ((cur.parms->count() == 1) && (cur.parms[0][0] == 0)) {
+		  if ((cur.parms->size() == 1) && (cur.parms->front() == 0)) {
 			delete cur.parms;
-			cur.parms = new svector<PExpr*>(0);
+			cur.parms = new list<PExpr*>;
 		  }
 		  pform_make_modgate(type, cur_name, overrides,
 				     cur.parms,
@@ -1667,7 +1671,7 @@ void pform_make_modgates(perm_string type,
 				     cur.file, cur.lineno);
 
 	    } else {
-		  svector<PExpr*>*wires = new svector<PExpr*>(0);
+		  list<PExpr*>*wires = new list<PExpr*>;
 		  pform_make_modgate(type, cur_name, overrides,
 				     wires,
 				     cur.range[0], cur.range[1],
@@ -1679,7 +1683,7 @@ void pform_make_modgates(perm_string type,
 }
 
 static PGAssign* pform_make_pgassign(PExpr*lval, PExpr*rval,
-			      svector<PExpr*>*del,
+			      list<PExpr*>*del,
 			      struct str_pair_t str)
 {
         /* Implicit declaration of nets on the LHS of a continuous
@@ -1687,9 +1691,9 @@ static PGAssign* pform_make_pgassign(PExpr*lval, PExpr*rval,
       if (generation_flag != GN_VER1995)
             pform_declare_implicit_nets(lval);
 
-      svector<PExpr*>*wires = new svector<PExpr*>(2);
-      (*wires)[0] = lval;
-      (*wires)[1] = rval;
+      list<PExpr*>*wires = new list<PExpr*>;
+      wires->push_back(lval);
+      wires->push_back(rval);
 
       PGAssign*cur;
 
@@ -1709,19 +1713,19 @@ static PGAssign* pform_make_pgassign(PExpr*lval, PExpr*rval,
       return cur;
 }
 
-void pform_make_pgassign_list(svector<PExpr*>*alist,
-			      svector<PExpr*>*del,
+void pform_make_pgassign_list(list<PExpr*>*alist,
+			      list<PExpr*>*del,
 			      struct str_pair_t str,
 			      const char* fn,
 			      unsigned lineno)
 {
-	PGAssign*tmp;
-	for (unsigned idx = 0 ;  idx < alist->count()/2 ;  idx += 1) {
-	      tmp = pform_make_pgassign((*alist)[2*idx],
-					(*alist)[2*idx+1],
-					del, str);
-	      FILE_NAME(tmp, fn, lineno);
-	}
+      assert(alist->size() % 2 == 0);
+      while (! alist->empty()) {
+	    PExpr*lval = alist->front(); alist->pop_front();
+	    PExpr*rval = alist->front(); alist->pop_front();
+	    PGAssign*tmp = pform_make_pgassign(lval, rval, del, str);
+	    FILE_NAME(tmp, fn, lineno);
+      }
 }
 
 /*
@@ -1783,7 +1787,7 @@ void pform_module_define_port(const struct vlltype&li,
 			      NetNet::Type type,
 			      ivl_variable_type_t data_type,
 			      bool signed_flag,
-			      svector<PExpr*>*range,
+			      list<PExpr*>*range,
 			      svector<named_pexpr_t*>*attr)
 {
       PWire*cur = pform_get_wire_in_scope(name);
@@ -1811,10 +1815,10 @@ void pform_module_define_port(const struct vlltype&li,
 	                   true);
 
       } else {
-	    assert(range->count() == 2);
-	    assert((*range)[0]);
-	    assert((*range)[1]);
-	    cur->set_range((*range)[0], (*range)[1],
+	    assert(range->size() == 2);
+	    assert(range->front());
+	    assert(range->back());
+	    cur->set_range(range->front(), range->back(),
 	                   (type == NetNet::IMPLICIT) ? SR_PORT : SR_BOTH,
 	                   false);
       }
@@ -1920,7 +1924,7 @@ void pform_makewire(const vlltype&li, perm_string name,
  * pform_makewire above.
  */
 void pform_makewire(const vlltype&li,
-		    svector<PExpr*>*range,
+		    list<PExpr*>*range,
 		    bool signed_flag,
 		    list<perm_string>*names,
 		    NetNet::Type type,
@@ -1948,9 +1952,9 @@ void pform_makewire(const vlltype&li,
  * This form makes nets with delays and continuous assignments.
  */
 void pform_makewire(const vlltype&li,
-		    svector<PExpr*>*range,
+		    list<PExpr*>*range,
 		    bool signed_flag,
-		    svector<PExpr*>*delay,
+		    list<PExpr*>*delay,
 		    str_pair_t str,
 		    net_decl_assign_t*decls,
 		    NetNet::Type type,
@@ -2058,7 +2062,7 @@ void pform_set_port_type(perm_string name, NetNet::PortType pt,
 svector<PWire*>*pform_make_task_ports(NetNet::PortType pt,
 				      ivl_variable_type_t vtype,
 				      bool signed_flag,
-				      svector<PExpr*>*range,
+				      list<PExpr*>*range,
 				      list<perm_string>*names,
 				      const char* file,
 				      unsigned lineno)
@@ -2084,8 +2088,10 @@ svector<PWire*>*pform_make_task_ports(NetNet::PortType pt,
 	    curw->set_signed(signed_flag);
 
 	      /* If there is a range involved, it needs to be set. */
-	    if (range)
-		  curw->set_range((*range)[0], (*range)[1], SR_PORT, false);
+	    if (range) {
+		  assert(range->size() == 2);
+		  curw->set_range(range->front(), range->back(), SR_PORT, false);
+	    }
 
 	    svector<PWire*>*tmp = new svector<PWire*>(*res, curw);
 
@@ -2166,7 +2172,7 @@ LexicalScope::range_t* pform_parameter_value_range(bool exclude_flag,
 
 void pform_set_parameter(const struct vlltype&loc,
 			 perm_string name, ivl_variable_type_t type,
-			 bool signed_flag, svector<PExpr*>*range, PExpr*expr,
+			 bool signed_flag, list<PExpr*>*range, PExpr*expr,
 			 LexicalScope::range_t*value_range)
 {
       LexicalScope*scope = lexical_scope;
@@ -2201,11 +2207,11 @@ void pform_set_parameter(const struct vlltype&loc,
 
       parm.type = type;
       if (range) {
-	    assert(range->count() == 2);
-	    assert((*range)[0]);
-	    assert((*range)[1]);
-	    parm.msb = (*range)[0];
-	    parm.lsb = (*range)[1];
+	    assert(range->size() == 2);
+	    assert(range->front());
+	    assert(range->back());
+	    parm.msb = range->front();
+	    parm.lsb = range->back();
       } else {
 	    parm.msb = 0;
 	    parm.lsb = 0;
@@ -2219,7 +2225,7 @@ void pform_set_parameter(const struct vlltype&loc,
 
 void pform_set_localparam(const struct vlltype&loc,
 			  perm_string name, ivl_variable_type_t type,
-			  bool signed_flag, svector<PExpr*>*range, PExpr*expr)
+			  bool signed_flag, list<PExpr*>*range, PExpr*expr)
 {
       LexicalScope*scope = lexical_scope;
 
@@ -2249,11 +2255,11 @@ void pform_set_localparam(const struct vlltype&loc,
 
       parm.type = type;
       if (range) {
-	    assert(range->count() == 2);
-	    assert((*range)[0]);
-	    assert((*range)[1]);
-	    parm.msb = (*range)[0];
-	    parm.lsb = (*range)[1];
+	    assert(range->size() == 2);
+	    assert(range->front());
+	    assert(range->back());
+	    parm.msb = range->front();
+	    parm.lsb = range->back();
       } else {
 	    parm.msb  = 0;
 	    parm.lsb  = 0;
@@ -2324,16 +2330,18 @@ extern PSpecPath*pform_make_specify_edge_path(const struct vlltype&li,
       return tmp;
 }
 
-extern PSpecPath* pform_assign_path_delay(PSpecPath*path, svector<PExpr*>*del)
+extern PSpecPath* pform_assign_path_delay(PSpecPath*path, list<PExpr*>*del)
 {
       if (path == 0)
 	    return 0;
 
       assert(path->delays.size() == 0);
 
-      path->delays.resize(del->count());
-      for (unsigned idx = 0 ;  idx < path->delays.size() ;  idx += 1)
-	    path->delays[idx] = (*del)[idx];
+      path->delays.resize(del->size());
+      for (unsigned idx = 0 ;  idx < path->delays.size() ;  idx += 1) {
+	    path->delays[idx] = del->front();
+	    del->pop_front();
+      }
 
       delete del;
 
@@ -2350,7 +2358,7 @@ extern void pform_module_specify_path(PSpecPath*obj)
 
 void pform_set_port_type(const struct vlltype&li,
 			 list<perm_string>*names,
-			 svector<PExpr*>*range,
+			 list<PExpr*>*range,
 			 bool signed_flag,
 			 NetNet::PortType pt)
 {
diff --git a/pform.h b/pform.h
index 9cce000a5..e263946be 100644
--- a/pform.h
+++ b/pform.h
@@ -89,7 +89,7 @@ typedef named<PExpr*> named_pexpr_t;
 typedef named<verinum> named_number_t;
 
 struct parmvalue_t {
-      svector<PExpr*>*by_order;
+      list<PExpr*>*by_order;
       svector<named_pexpr_t*>*by_name;
 };
 
@@ -105,7 +105,7 @@ struct net_decl_assign_t {
 struct enum_type_t {
       ivl_variable_type_t base_type;
       bool signed_flag;
-      auto_ptr< svector<PExpr*> > range;
+      auto_ptr< list<PExpr*> > range;
       auto_ptr< list<named_number_t> > names;
 };
 
@@ -118,7 +118,7 @@ struct lgate {
       }
 
       string name;
-      svector<PExpr*>*parms;
+      list<PExpr*>*parms;
       svector<named_pexpr_t*>*parms_by_name;
 
       PExpr*range[2];
@@ -165,7 +165,7 @@ extern void pform_module_define_port(const struct vlltype&li,
 				     NetNet::Type type,
 				     ivl_variable_type_t data_type,
 				     bool signed_flag,
-				     svector<PExpr*>*range,
+				     list<PExpr*>*range,
 				     svector<named_pexpr_t*>*attr);
 
 extern Module::port_t* pform_module_port_reference(perm_string name,
@@ -220,7 +220,7 @@ extern void pform_start_generate_if(const struct vlltype&li, PExpr*test);
 extern void pform_start_generate_else(const struct vlltype&li);
 extern void pform_start_generate_case(const struct vlltype&lp, PExpr*test);
 extern void pform_start_generate_nblock(const struct vlltype&lp, char*name);
-extern void pform_generate_case_item(const struct vlltype&lp, svector<PExpr*>*test);
+extern void pform_generate_case_item(const struct vlltype&lp, list<PExpr*>*test);
 extern void pform_generate_block_name(char*name);
 extern void pform_endgenerate();
 
@@ -243,7 +243,7 @@ extern void pform_makewire(const struct vlltype&li, perm_string name,
 
 /* This form handles simple declarations */
 extern void pform_makewire(const struct vlltype&li,
-			   svector<PExpr*>*range,
+			   list<PExpr*>*range,
 			   bool signed_flag,
 			   list<perm_string>*names,
 			   NetNet::Type type,
@@ -254,9 +254,9 @@ extern void pform_makewire(const struct vlltype&li,
 
 /* This form handles assignment declarations. */
 extern void pform_makewire(const struct vlltype&li,
-			   svector<PExpr*>*range,
+			   list<PExpr*>*range,
 			   bool signed_flag,
-			   svector<PExpr*>*delay,
+			   list<PExpr*>*delay,
 			   str_pair_t str,
 			   net_decl_assign_t*assign_list,
 			   NetNet::Type type,
@@ -270,14 +270,14 @@ extern void pform_make_reginit(const struct vlltype&li,
      it. The second form takes a single name. */
 extern void pform_set_port_type(const struct vlltype&li,
 				list<perm_string>*names,
-				svector<PExpr*>*range,
+				list<PExpr*>*range,
 				bool signed_flag,
 				NetNet::PortType);
 extern void pform_set_port_type(perm_string nm, NetNet::PortType pt,
 				const char*file, unsigned lineno);
 
 extern void pform_set_net_range(list<perm_string>*names,
-				svector<PExpr*>*,
+				list<PExpr*>*,
 				bool signed_flag,
 				ivl_variable_type_t,
 				PWSRType rt = SR_NET);
@@ -306,13 +306,13 @@ extern void pform_set_parameter(const struct vlltype&loc,
 				perm_string name,
 				ivl_variable_type_t type,
 				bool signed_flag,
-				svector<PExpr*>*range,
+				list<PExpr*>*range,
 				PExpr*expr, LexicalScope::range_t*value_range);
 extern void pform_set_localparam(const struct vlltype&loc,
 				 perm_string name,
 				 ivl_variable_type_t type,
 				 bool signed_flag,
-				 svector<PExpr*>*range,
+				 list<PExpr*>*range,
 				 PExpr*expr);
 extern void pform_set_defparam(const pform_name_t&name, PExpr*expr);
 
@@ -329,7 +329,7 @@ extern PSpecPath*pform_make_specify_edge_path(const struct vlltype&li,
 					 list<perm_string>*src, char pol,
 					 bool full_flag, list<perm_string>*dst,
 					 PExpr*data_source_expression);
-extern PSpecPath*pform_assign_path_delay(PSpecPath*obj, svector<PExpr*>*delays);
+extern PSpecPath*pform_assign_path_delay(PSpecPath*obj, list<PExpr*>*delays);
 
 extern void pform_module_specify_path(PSpecPath*obj);
 
@@ -356,7 +356,7 @@ extern void pform_make_reals(list<perm_string>*names,
  */
 extern void pform_makegates(PGBuiltin::Type type,
 			    struct str_pair_t str,
-			    svector<PExpr*>*delay,
+			    list<PExpr*>*delay,
 			    svector<lgate>*gates,
 			    svector<named_pexpr_t*>*attr);
 
@@ -365,8 +365,8 @@ extern void pform_make_modgates(perm_string type,
 				svector<lgate>*gates);
 
 /* Make a continuous assignment node, with optional bit- or part- select. */
-extern void pform_make_pgassign_list(svector<PExpr*>*alist,
-				     svector<PExpr*>*del,
+extern void pform_make_pgassign_list(list<PExpr*>*alist,
+				     list<PExpr*>*del,
 				     struct str_pair_t str,
 				     const char* fn, unsigned lineno);
 
@@ -375,7 +375,7 @@ extern void pform_make_pgassign_list(svector<PExpr*>*alist,
 extern svector<PWire*>*pform_make_task_ports(NetNet::PortType pt,
 					     ivl_variable_type_t vtype,
 					     bool signed_flag,
-					     svector<PExpr*>*range,
+					     list<PExpr*>*range,
 					     list<perm_string>*names,
 					     const char* file,
 					     unsigned lineno);
diff --git a/pform_dump.cc b/pform_dump.cc
index cbef88cc1..db3aa7e25 100644
--- a/pform_dump.cc
+++ b/pform_dump.cc
@@ -169,14 +169,14 @@ void PEConcat::dump(ostream&out) const
       if (repeat_)
 	    out << "{" << *repeat_;
 
-      if (parms_.count() == 0) {
+      if (parms_.size() == 0) {
 	    out << "{}";
 	    return;
       }
 
       out << "{";
       if (parms_[0]) out << *parms_[0];
-      for (unsigned idx = 1 ;  idx < parms_.count() ;  idx += 1) {
+      for (unsigned idx = 1 ;  idx < parms_.size() ;  idx += 1) {
 	    out << ", ";
 	    if (parms_[idx]) out << *parms_[idx];
       }
@@ -478,16 +478,18 @@ void PGModule::dump(ostream&out, unsigned ind) const
       out << setw(ind) << "" << type_ << " ";
 
 	// If parameters are overridden by order, dump them.
-      if (overrides_ && overrides_->count() > 0) {
+      if (overrides_ && overrides_->size() > 0) {
 	    assert(parms_ == 0);
             out << "#(";
 
-	    if ((*overrides_)[0] == 0)
+	    list<PExpr*>::const_iterator idx = overrides_->begin();
+
+	    if (*idx == 0)
 		  out << "<nil>";
 	    else
-		  out << *((*overrides_)[0]);
-	    for (unsigned idx = 1 ;  idx < overrides_->count() ;  idx += 1) {
-	          out << "," << *((*overrides_)[idx]);
+		  out << *idx;
+	    for ( ;  idx != overrides_->end() ;  ++ idx) {
+	          out << "," << *idx;
 	    }
 	    out << ") ";
       }
@@ -600,12 +602,12 @@ void PCallTask::dump(ostream&out, unsigned ind) const
 {
       out << setw(ind) << "" << path_;
 
-      if (parms_.count() > 0) {
+      if (parms_.size() > 0) {
 	    out << "(";
 	    if (parms_[0])
 		  out << *parms_[0];
 
-	    for (unsigned idx = 1 ;  idx < parms_.count() ;  idx += 1) {
+	    for (unsigned idx = 1 ;  idx < parms_.size() ;  idx += 1) {
 		  out << ", ";
 		  if (parms_[idx])
 			out << *parms_[idx];
@@ -636,14 +638,15 @@ void PCase::dump(ostream&out, unsigned ind) const
       for (unsigned idx = 0 ;  idx < items_->count() ;  idx += 1) {
 	    PCase::Item*cur = (*items_)[idx];
 
-	    if (cur->expr.count() == 0) {
+	    if (cur->expr.size() == 0) {
 		  out << setw(ind+2) << "" << "default:";
 
 	    } else {
-		  out << setw(ind+2) << "" << *cur->expr[0];
+		  list<PExpr*>::iterator idx_exp = cur->expr.begin();
+		  out << setw(ind+2) << "" << *idx_exp;
 
-		  for(unsigned e = 1 ; e < cur->expr.count() ; e += 1)
-			out << ", " << *cur->expr[e];
+		  for( ; idx_exp != cur->expr.end() ; ++idx_exp)
+			out << ", " << *idx_exp;
 
 		  out << ":";
 	    }
diff --git a/util.h b/util.h
index 29f208dce..64de121a2 100644
--- a/util.h
+++ b/util.h
@@ -20,6 +20,8 @@
  */
 
 # include  <map>
+# include  <vector>
+# include  <list>
 # include  "StringHeap.h"
 # include  "verinum.h"