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+===== Using Verilog circuits in a SPICE-only simulator =====
+Some SPICE simulators do not understand Verilog syntax or semantics. A subset of the structural part of Verilog maps nicely to Spice, given a library
+ that maps devices to a representation that works with the targeted Spice engine.
+==== The mechanism ====
+A device instance has a type, a label as well as parameter and port assignments.
+<code>
+mytype #(.myparameter(42)) mylabel(.someport(a), .otherport(b));
+</code>
+There is little hope for an automatic conversion to spice, due to the irregular syntax. A string template can be used to carry a representation that a spice simulator will understand. For example (see CanEDA or KiCAD for real world spice instance templates) an instance could carry a template as follows.
+<code>
+(* some_spice="R${label} ${port[someport]} ${port[otherport]} ${par[value]} *)
+mytype #(.value(42)) mydevice(.otherport(b), .someport(a));
+</code>
+With this, an automatic transcription will be feasible (here, targetting "some_spice"), and result in
+<code>Rmydevice b a 42</code>
+Note that the circuit containing mydevice is still compliant with Verilog syntax, and understood by compliant tools.
+==== Decoupling metadata ====
+In order to decouple circuits from simulator specifics, string templates can be moved to a device library for use in a specific (Spice) simulator.
+This completely makes up for the missing Verilog support in a simulator.
+Suppose a circuit contains an instance similar to the example above, but without any knowledge about Spice specifics or their variants.
+<code>
+mytype #(.value(42)) mydevice2(.otherport(b), .someport(a));
+</code>
+A library file (ideally provided by Spice simulator maintainers) may provide the additional mapping template withuout interference.
+<code>
+(* some_other_spice="X${label} (${port[someport]} ${port[otherport]}) value=${par[value]} *)
+module mytype(otherport, someport);
+parameter value=0;
+endmodule
+</code>
+Which will instruct the exporter to represent mydevice2 as
+<code>
+Xmydevice (b a) value=42
+</code>
+When targeting some other Spice.
+==== Examples ====
+=== Resistor ===
+A resistor declaration such as
+<code>
+(* spice="R${label} (${port[p]} ${port[n]}) ${par[r]}" *)
+module resistor(p, n);
+  parameter real r=1;
+endmodule
+</code>
+should work with nearly any spice simulator.
+=== The net device ===
+A net device could be defined as follows
+<code>
+(* ngspice="R${label} (${port[a]} ${port[b]}) 0" *)
+module net(.a(i), .b(i));
+endmodule
+</code>
+And instances of it will now swiftly work with ngSpice (after the export).