This option serves to specify the unit path, where the compiler looks for unit files. {$UNITPATH XXX} will add XXX to the unit path. XXX can contain one or more paths, separated by semi-colons or colons.
For example:
will add the directories ../units and ../i386/units to the unit path of the compiler. The compiler will look for the file strings.ppu in both these directories, and will link the first found file in the program. This directive is equivalent to the -Fu command line switch.
Caution is in order when using this directive: If you distribute files, the places of the files may not be the same as on your machine; moreover, the directory structure may be different. In general it would be fair to say that you should avoid using absolute paths, instead use relative paths, as in the example above. Only use this directive if you are certain of the places where the files reside. If you are not sure, it is better practice to use makefiles and makefile variables.
Note that this switch does not propagate to other units, i.e. it’s scope is limited to the current unit.