RPM - spec - Directory Standarization

FHS structure is making me crazy and I need to write down things since I forget how that FHS craziness works.

Testing
You can open sh command line session and test:

/@unixroot/usr/share/os2/lang /@unixroot/usr/share/os2/book /@unixroot/usr/share/os2/help F:\Apps\myapp $PROGRAMS\\myapp
 * 1) rpm --eval %os2_langdir
 * 1) rpm --eval %os2_bookdir
 * 1) rpm --eval %os2_helpdir
 * 1) rpm --eval %{echo:$PROGRAMS\\myapp}
 * 1) rpm --eval %{echo:$PROGRAMS\\myapp}

Links

 * XDG Base Directory Specification