Once the local library's headers and module-compiled headers are available via
the local library's tt(hdr) sub-directory they can be imported by source
files which do not belong to the library. 

Suppose the library's header files are imported by tt(main.cc), defined in the
directory tt(~/project):
    verbinclude(-as4 examples/locallibabs/main.cc)

Furthermore, assume the local library's top-level directory is
tt(~/support/locallib) (and so tt(~/support/locallib/hdrs) contains the
soft-links to its header files and module-compiled header files).

To make the library's headers available to tt(main.cc) two soft-links to
relative destinations can be defined:
    itemization(
    it() in tt(~/project) define a soft-link to the library's tt(hdrs)
        directory: 
 verb(    ln -s ../support/locallib/hdrs .)
    it() in the tt(~/project/gcm.cache/,/) (note: comma!) sub-directory define
        a soft-link to the just defined tt(hdrs) soft-link:
 verb(    ln -s ../../hdrs .)
    )

Once these links are available tt(main.cc) can be compiled using
 verb(    g++ -c --std=c++26 -fmodules-ts -isystem hdrs main.cc)

    itemization(
    it() In practice the program using the library's headers also needs linker
        options: these are used as always, and need no further modifications.
    it() The soft-links must be relative links: if the local library's tt(hdr)
        is located in a completely different location then the soft-link
        tt(~/project/hdrs) must point to that directory using a relative path
        specification. 
    it() The names of the two soft-links must be identical, but the name of
        the project's soft-link to the library's tt(hdrs) directory does not
        have to be tt(hdrs).
    )
    
