diff --git a/doc/xschem_man/tutorial_symbol_generators.html b/doc/xschem_man/tutorial_symbol_generators.html
new file mode 100644
index 00000000..391042e3
--- /dev/null
+++ b/doc/xschem_man/tutorial_symbol_generators.html
@@ -0,0 +1,29 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title>XSCHEM TUTORIAL: SYMBOL GENERATORS</title>
+<link rel="stylesheet" type="text/css" href="xschem_man.css" />
+<style type="text/css">
+/* Local styling goes here */
+p{padding: 15px  30px 10px;}
+</style>
+
+</head>
+<body>
+
+<!-- start of slide -->
+<div class="content">   
+<!-- navigation buttons -->
+<a href="xschem_man.html" class="home">UP</a>
+
+ <!-- slide title -->
+ <h1> TUTORIAL: SYMBOL GENERATORS</h1>
+ <!-- end of slide -->
+ <div class="filler"></div>
+</div>
+
+<!-- frame footer -->
+<iframe seamless src="xschem_footer.html"  class="footer_iframe" >
+</body>
+</html>
+
diff --git a/doc/xschem_man/xschem_man.html b/doc/xschem_man/xschem_man.html
index 595ec503..57de6a3b 100644
--- a/doc/xschem_man/xschem_man.html
+++ b/doc/xschem_man/xschem_man.html
@@ -57,6 +57,7 @@
  <li><a href="tutorial_install_xschem.html">Step by step instructions: Install XSCHEM</a></li>
  <li><a href="tutorial_run_simulation.html">Run a simulation with XSCHEM</a></li>
  <li><a href="tutorial_instance_based_implementation.html">Instance based selection of symbol implementation</a></li>
+ <li><a href="tutorial_symbol_generators.html">Symbol generators</a></li>
  <li><a href="tutorial_use_existing_subckt.html">Create a symbol and use an existing subcircuit netlist</a></li>
  <li><a href="tutorial_create_symbol.html">Create a symbol with XSCHEM</a></li>
  <li><a href="tutorial_xschem_libraries.html">Manage XSCHEM design libraries / symbol librares</a></li>
diff --git a/src/scheduler.c b/src/scheduler.c
index 4073b092..e1068ffd 100644
--- a/src/scheduler.c
+++ b/src/scheduler.c
@@ -1765,6 +1765,17 @@ int xschem(ClientData clientdata, Tcl_Interp *interp, int argc, const char * arg
       Tcl_SetResult(interp, pins ? pins : "", TCL_VOLATILE);
       my_free(_ALLOC_ID_, &pins);
     }
+
+    /* is_symgen symbol
+     *   tell if 'symbol' is agenerator (symbol(param1,param2,...) */
+    else if(!strcmp(argv[1], "is_symgen"))
+    {       
+      char s[30];
+      if(argc > 2) {
+        my_snprintf(s, S(s), "%d", is_symgen(argv[2]));
+        Tcl_SetResult(interp, s, TCL_VOLATILE);
+      } 
+    } 
     else { cmd_found = 0;}
     break;
     case 'l': /*----------------------------------------------*/
diff --git a/src/token.c b/src/token.c
index 0637f4ff..544b33fc 100644
--- a/src/token.c
+++ b/src/token.c
@@ -176,9 +176,10 @@ int is_symgen(const char *name)
   }
   if(!re) {
     re = my_malloc(_ALLOC_ID_, sizeof(regex_t));
-    regcomp(re, "^[^ \\t()]+\\([^()]*\\)[ \\t]*$", REG_NOSUB | REG_EXTENDED);
+    regcomp(re, "^[^ \t()]+\\([^()]*\\)[ \t]*$", REG_NOSUB | REG_EXTENDED);
   }
   if(!regexec(re, name, 0 , NULL, 0) ) res = 1;
+  dbg(1, "is_symgen(%s)=%d\n", name, res);
   /* regfree(&re); */
   return res;
   #else
@@ -202,9 +203,10 @@ int match_symbol(const char *name)  /* never returns -1, if symbol not found loa
  }
  if(!found)
  {
-   dbg(1, "match_symbol(): matching symbol not found:%s, loading\n",name);
+   dbg(1, "match_symbol(): matching symbol not found: loading\n");
    
    if(!is_symgen(name)) {
+     dbg(1, "match_symbol(): symbol=%s\n",name);
      load_sym_def(name, NULL, 0); /* append another symbol to the xctx->sym[] array */
    } else { /* get symbol from generator script */
      FILE *fp;
@@ -214,6 +216,7 @@ int match_symbol(const char *name)  /* never returns -1, if symbol not found loa
      char *spc_idx;
      struct stat buf;
  
+     dbg(1, "match_symbol(): symgen=%s\n",name);
      cmd = str_chars_replace(name, " (),", ' ');
      spc_idx = strchr(cmd, ' ');
      if(!spc_idx) goto end;
diff --git a/xschem_library/ngspice/adc.sch b/xschem_library/ngspice/adc.sch
index 15c99033..5c4b50ff 100644
--- a/xschem_library/ngspice/adc.sch
+++ b/xschem_library/ngspice/adc.sch
@@ -1,4 +1,5 @@
-v {xschem version=3.0.0 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {}
 V {}
@@ -102,16 +103,19 @@ C {ipin.sym} 640 -190 0 0 {name=p10 lab=CK}
 C {ipin.sym} 640 -150 0 0 {name=p11 lab=RST}
 C {lab_pin.sym} 790 -170 0 0 {name=p14 lab=VCC}
 C {lab_pin.sym} 950 -190 0 1 {name=p24 lab=C[5:0]}
-C {and3_ngspice.sym} 1120 -230 0 0 {name=x5 ROUT=1000}
+C {and3_ngspice.sym} 1120 -230 0 0 {name=x5 ROUT=1000 net_name=true}
 C {lab_pin.sym} 1080 -250 0 0 {name=p25 lab=C[5]}
 C {lab_pin.sym} 1080 -230 0 0 {name=p26 lab=C[4]}
 C {lab_pin.sym} 1080 -210 0 0 {name=p27 lab=C[3]}
 C {lab_pin.sym} 1080 -150 0 0 {name=p28 lab=C[1]}
 C {lab_pin.sym} 1080 -130 0 0 {name=p29 lab=C[0]}
-C {and3_ngspice.sym} 1120 -150 0 0 {name=x6 ROUT=1000}
+C {and3_ngspice.sym} 1120 -150 0 0 {name=x6 ROUT=1000
+net_name=true}
 C {lab_pin.sym} 1080 -170 0 0 {name=p30 lab=C[2]}
-C {and_ngspice.sym} 1220 -190 0 0 {name=x7 ROUT=1000}
-C {or_ngspice.sym} 1320 -210 0 0 {name=x8 ROUT=1000}
+C {and_ngspice.sym} 1220 -190 0 0 {name=x7 ROUT=1000
+net_name=true}
+C {or_ngspice.sym} 1320 -210 0 0 {name=x8 ROUT=1000
+net_name=true}
 C {lab_pin.sym} 1280 -230 0 0 {name=p31 lab=RST}
 C {lab_pin.sym} 1540 -230 0 1 {name=p15 lab=RSTI}
 C {flip_flop_ngspice.sym} 1480 -210 0 0 {name=x9}
@@ -121,7 +125,7 @@ C {lab_pin.sym} 1520 -390 0 0 {name=p1 lab=RST}
 C {spice_probe.sym} 840 -250 0 0 {name=p6 attrs=""}
 C {spice_probe.sym} 710 -410 0 0 {name=p17 attrs=""}
 C {spice_probe.sym} 1540 -270 0 0 {name=p18 attrs=""}
-C {inv_ngspice.sym} 1040 -410 0 0 {name=x11 ROUT=1000}
+C {inv_ngspice.sym} 1040 -410 0 0 {name=x11 ROUT=1000 net_name=true}
 C {lab_wire.sym} 1130 -410 0 0 {name=l2 lab=QN}
 C {spice_probe.sym} 1090 -410 0 0 {name=p19 attrs=""}
 C {ipin.sym} 310 -370 0 0 {name=p242 lab=VREF}
@@ -145,4 +149,4 @@ C {spice_probe.sym} 220 -430 0 0 {name=p265 attrs=""}
 C {opamp_65nm.sym} 380 -400 2 1 {name=x41}
 C {comp_65nm.sym} 610 -410 0 0 {name=x42}
 C {spice_probe.sym} 1470 -430 0 0 {name=p2 attrs=""}
-C {or_ngspice.sym} 1110 -320 0 0 {name=x3 ROUT=1000}
+C {or_ngspice.sym} 1110 -320 0 0 {name=x3 ROUT=1000 net_name=true}
diff --git a/xschem_library/ngspice/and3_ngspice.sch b/xschem_library/ngspice/and3_ngspice.sch
index 12d20c28..8e87002c 100644
--- a/xschem_library/ngspice/and3_ngspice.sch
+++ b/xschem_library/ngspice/and3_ngspice.sch
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {}
 V {}
@@ -18,7 +19,7 @@ C {bsource.sym} 480 -330 0 1 {name=B1 VAR=V FUNC="'VCC/2*(1+tanh((min(V(C1),min(
 C {lab_pin.sym} 310 -400 0 0 {name=l2 sig_type=std_logic lab=A1}
 C {lab_pin.sym} 480 -250 0 0 {name=l3 sig_type=std_logic lab=0}
 C {res.sym} 580 -400 1 0 {name=R1
-value='ROUT'
+value=ROUT
 footprint=1206
 device=resistor
 m=1}
diff --git a/xschem_library/ngspice/and3_ngspice.sym b/xschem_library/ngspice/and3_ngspice.sym
index aa8997d1..ae890732 100644
--- a/xschem_library/ngspice/and3_ngspice.sym
+++ b/xschem_library/ngspice/and3_ngspice.sym
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {type=subcircuit
 format="@name @pinlist @symname ROUT=@ROUT"
@@ -19,3 +20,7 @@ B 5 -42.5 -2.5 -37.5 2.5 {name=B dir=in}
 B 5 -42.5 17.5 -37.5 22.5 {name=C dir=in}
 A 4 5 0 30 270 180 {}
 T {@name} -16.25 -5 0 0 0.2 0.2 {}
+T {@#1:net_name} -22.5 -17.5 0 1 0.15 0.15 {layer=15}
+T {@#0:net_name} 35 1.25 0 0 0.15 0.15 {layer=15}
+T {@#2:net_name} -22.5 2.5 0 1 0.15 0.15 {layer=15}
+T {@#3:net_name} -22.5 22.5 0 1 0.15 0.15 {layer=15}
diff --git a/xschem_library/ngspice/and_ngspice.sch b/xschem_library/ngspice/and_ngspice.sch
index 4bf1c940..8006e262 100644
--- a/xschem_library/ngspice/and_ngspice.sch
+++ b/xschem_library/ngspice/and_ngspice.sch
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {}
 V {}
@@ -17,7 +18,7 @@ C {bsource.sym} 480 -330 0 1 {name=B1 VAR=V FUNC="'VCC/2*(1+tanh((min(V(A1),V(B1
 C {lab_pin.sym} 330 -400 0 0 {name=l2 sig_type=std_logic lab=A1}
 C {lab_pin.sym} 480 -250 0 0 {name=l3 sig_type=std_logic lab=0}
 C {res.sym} 580 -400 1 0 {name=R1
-value='ROUT'
+value=ROUT
 footprint=1206
 device=resistor
 m=1}
diff --git a/xschem_library/ngspice/and_ngspice.sym b/xschem_library/ngspice/and_ngspice.sym
index 9b1bdaf7..03606058 100644
--- a/xschem_library/ngspice/and_ngspice.sym
+++ b/xschem_library/ngspice/and_ngspice.sym
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {type=subcircuit
 format="@name @pinlist @symname ROUT=@ROUT"
@@ -17,3 +18,6 @@ B 5 -42.5 -22.5 -37.5 -17.5 {name=A dir=in}
 B 5 -42.5 17.5 -37.5 22.5 {name=B dir=in}
 A 4 5 0 30 270 180 {}
 T {@name} -16.25 -5 0 0 0.2 0.2 {}
+T {@#1:net_name} -22.5 -17.5 0 1 0.15 0.15 {layer=15}
+T {@#0:net_name} 35 1.25 0 0 0.15 0.15 {layer=15}
+T {@#3:net_name} -22.5 22.5 0 1 0.15 0.15 {layer=15}
diff --git a/xschem_library/ngspice/buf_ngspice.sch b/xschem_library/ngspice/buf_ngspice.sch
index ebc44a53..f06a7926 100644
--- a/xschem_library/ngspice/buf_ngspice.sch
+++ b/xschem_library/ngspice/buf_ngspice.sch
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {}
 V {}
@@ -17,7 +18,7 @@ C {bsource.sym} 470 -400 0 1 {name=B1 VAR=V FUNC="'VCC/2*(1+tanh((V(A1)-VCC/2)*1
 C {lab_pin.sym} 320 -470 0 0 {name=l2 sig_type=std_logic lab=A1}
 C {lab_pin.sym} 470 -320 0 0 {name=l3 sig_type=std_logic lab=0}
 C {res.sym} 570 -470 1 0 {name=R1
-value='ROUT'
+value=ROUT
 footprint=1206
 device=resistor
 m=1}
diff --git a/xschem_library/ngspice/buf_ngspice.sym b/xschem_library/ngspice/buf_ngspice.sym
index d8ddff9d..d9e06b55 100644
--- a/xschem_library/ngspice/buf_ngspice.sym
+++ b/xschem_library/ngspice/buf_ngspice.sym
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {type=subcircuit
 format="@name @pinlist @symname ROUT=@ROUT"
@@ -19,3 +20,5 @@ T {@name} 25 -22 0 0 0.2 0.2 {}
 T {Y} 7.5 -6.5 0 1 0.2 0.2 {}
 T {A} -17.5 -6.5 0 0 0.2 0.2 {}
 T {ROUT=@ROUT} -25 -42 0 0 0.2 0.2 {}
+T {@#1:net_name} -22.5 6.25 0 1 0.15 0.15 {layer=15}
+T {@#0:net_name} 17.5 6.25 0 0 0.15 0.15 {layer=15}
diff --git a/xschem_library/ngspice/inv_ngspice.sch b/xschem_library/ngspice/inv_ngspice.sch
index 23a91ffd..34033e8c 100644
--- a/xschem_library/ngspice/inv_ngspice.sch
+++ b/xschem_library/ngspice/inv_ngspice.sch
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {}
 V {}
@@ -17,7 +18,7 @@ C {bsource.sym} 470 -400 0 1 {name=B1 VAR=V FUNC="'VCC/2*(1-tanh((V(A1)-VCC/2)*1
 C {lab_pin.sym} 320 -470 0 0 {name=l2 sig_type=std_logic lab=A1}
 C {lab_pin.sym} 470 -320 0 0 {name=l3 sig_type=std_logic lab=0}
 C {res.sym} 570 -470 1 0 {name=R1
-value='ROUT'
+value=ROUT
 footprint=1206
 device=resistor
 m=1}
diff --git a/xschem_library/ngspice/inv_ngspice.sym b/xschem_library/ngspice/inv_ngspice.sym
index 1d15b7c0..76ae8566 100644
--- a/xschem_library/ngspice/inv_ngspice.sym
+++ b/xschem_library/ngspice/inv_ngspice.sym
@@ -25,5 +25,5 @@ T {@name} 25 -22 0 0 0.2 0.2 {}
 T {Y} 7.5 -6.5 0 1 0.2 0.2 {}
 T {A} -17.5 -6.5 0 0 0.2 0.2 {}
 T {ROUT=@ROUT} -25 -42 0 0 0.2 0.2 {}
-T {@#1:net_name} -40 6.25 0 0 0.15 0.15 {layer=15}
-T {@#0:net_name} 40 6.25 0 1 0.15 0.15 {layer=15}
+T {@#1:net_name} -22.5 6.25 0 1 0.15 0.15 {layer=15}
+T {@#0:net_name} 17.5 6.25 0 0 0.15 0.15 {layer=15}
diff --git a/xschem_library/ngspice/or_ngspice.sym b/xschem_library/ngspice/or_ngspice.sym
index 610c4de7..b303ab0a 100644
--- a/xschem_library/ngspice/or_ngspice.sym
+++ b/xschem_library/ngspice/or_ngspice.sym
@@ -1,4 +1,5 @@
-v {xschem version=2.9.9 file_version=1.2 }
+v {xschem version=3.1.0 file_version=1.2
+}
 G {}
 K {type=subcircuit
 format="@name @pinlist @symname ROUT=@ROUT"
@@ -18,3 +19,6 @@ A 4 -65 0 50 323.130102354156 73.7397952916881 {}
 A 4 -9.642857142857142 17.85714285714286 48.0818286351295 21.80140948635181 62.65738573560834 {}
 A 4 -4.6875 -11.25 41.25118369513777 269.5659493678606 74.60789655596687 {}
 T {@name} -11.25 -5 0 0 0.2 0.2 {}
+T {@#1:net_name} -20 -18.75 0 1 0.15 0.15 {layer=15}
+T {@#0:net_name} 35 1.25 0 0 0.15 0.15 {layer=15}
+T {@#2:net_name} -20 10 0 1 0.15 0.15 {layer=15}
