xschem

If you have for example the following definition in a file, say symbol_include.cir:

* example of a subcircuit contained in a file

.subckt symbol_include Z VCC VSS
+ A B C W=10 L=1
...
...
.ends

You can use this file to get the spice netlist port order:

In the following testbench:

the symbol is defined as follows:

When netlisting the testbench the port order (the @pinlist in the format string) of the x1 instance call will match the order in the file symbol_include.cir:

** sch_path: /home/schippes/.xschem/xschem_library/symbol_include/tb_symbol_include.sch
**.subckt tb_symbol_include XZ XVSS XVCC XC XB XA
*.opin XZ
*.ipin XVSS
*.ipin XVCC
*.ipin XC
*.ipin XB
*.ipin XA
x1 XZ XVCC XVSS XA XB XC symbol_include
**.ends

* expanding   symbol:  symbol_include.sym # of pins=6
** sym_path: /home/schippes/.xschem/xschem_library/symbol_include/symbol_include.sym
.include symbol_include.cir
.end

A final note, the spice_sym_def does not necessarily need to use a .include line. You can directly define the subcircuit:

spice_sym_def="
.subckt symbol_include Z VCC VSS
+ A B C
...
...
.ends
"