General form:

XYYYYYYY N1 <N2 N3 ...> SUBNAM

Examples:

X1 2 4 17 3 1 MULTI

Subcircuits are used in ngspice by specifying pseudo-elements beginning with the letter X, followed by the circuit nodes to be used in expanding the subcircuit. If you use parameters, the subcircuit call will be modified (see 2.8.3).