3.4. .includeSearch Path: -Ipath

Use this option to add a path to the list of directories as searches for files specified in .include directives (refer to Section 8.45 .include "file"). You may use -I as many times as necessary to include a variety of paths. The current working directory is always searched first; after that, as searches any -I directories in the same order as they were specified (left to right) on the command line.