doc updates (pinnumber)

doc/xschem_man/symbol_property_syntax.html

@@ -89,8 +89,8 @@ p{padding: 15px  30px 10px;}
      </li>
      <img src="spiceprefix.png">
  <li><kbd>template</kbd>: Specifies default values for symbol parameters</li>
- </ul>
 <img src="general_rules.png">
+ </ul>
  <p>
   The order these attributes appear in the property string is not important, 
   they can be on the same line or on different lines:
@@ -338,6 +338,40 @@ m5 net1 b net2 VSSPIN nlv w=wn l=ln geomod=0 m=1
    Defines the direction of a symbol pin. Allowed values are <kbd>in</kbd>, <kbd>out</kbd>, <kbd>inout</kbd>.
   </p>
    <img src="symbol_property_syntax2.png">
+
+  <li><kbd>pinnumber</kbd></li>
+  <p> 
+   For packaged devices (tEDAx netlists) : indicate the position of the pin on the package.
+   This can be overriden at instance level by attributes <kbd>pinnumber(name)</kbd> set in the instance
+   for tEDAx netlists.
+   <br><br>
+   For VHDL, SPICE, Verilog netlists: define the ordering of symbol ports in netlist.
+   If all symbol pins have a pinnumber attribute this symbol will be netlisted 
+   (in all netlist formats) with pins sorted in ascending order according to pinnumber value.
+   Start value of pinnumber does not matter (may start at 1 or 0) , it is used as the sort key.
+   You can assign the pinnumber attribute directly in the symbol...
+  </p>
+  <img src="pinnumber1.png">
+  <p>
+  ... Or you can assign these in the schematic pins, if you use the "Make symbol from schematic"
+  function ('a' key) these attributes will be transferred to the symbol.<br>
+  The pinnumber attributes that determine the netlist port ordering are those defined in the symbol.
+  </p>
+  <img src="pinnumber2.png">
+  <p>
+  For sorting to happen all symbol pins must have a pinnumber attribute.
+  If some pins miss this attribute no sorting is done and pin ordering will be unchanged,
+  the stored order of symbol pins will be used (first created pin netlisted first).<br>
+  If there are duplicate pinnumber attributes (but all pins have this attribute) sorting
+  will happen but relative ordering or pins with identical pinnumber is undefined.<br>
+  As an example you may give pinnumber=9999 on a symbol output and pinnumber=1 on all other
+  pins if you only require the output pin to be netlisted at the end, and don't care about
+  the other pin ordering.
+  </p>
+
+
+
+
   <li><kbd>propag=n</kbd></li>
   <p>
   This attribute instructs xschem to do a 'propagate highlight' from the pin with this attribute to the