General form:

.INCLUDE filename

Examples:

.INCLUDE /users/spice/common/bsim3-param.mod

Frequently, portions of circuit descriptions will be reused in several input files, particularly with common models and subcircuits. In any ngspice input file, the .INCLUDE line may be used to copy some other file as if that second file appeared in place of the .INCLUDE line in the original file.

There is no restriction on the file name imposed by ngspice beyond those imposed by the local operating system.