@User once you create a symbol in xschem (for example assume an opamp), with some input pins some outputs and power nets, the actual implementation of the circuit can be given as a netlist imported as pure code, instead of drawing the circuit schematic. This is often done when simulating netlists extracted from the layout (which include parasitic effects). See pictures below, if you descend into the opamp symbol there is no circuit, however if you press 'q' (edit global attributes) you can press the 'Load' button to load the appropriate netlist. You can also bind a different schematic to a given symbol, as explained at 4'.10" in this video. This allows you to easily switch from a circuit schematic to an empty schematc containing an imported netlist.

Okay thanks a lot for the @User. Its really helpful!!!

@User if you import an external netlist into a symbol schematic ensure you comment out the

.subckt

and

.ends

lines (if any) since xschem will create these lines when expanding the symbol into the final spice netlist.

Ok thanks @User