compare:

-defaultlib=libname  Link in libname [...].

and

-fPIC generate Position Independent Code (...).
-Hd write D interface file to $(I dir) directory.

most of the descriptions start with lower case, even if they end with a period, while the new ones use upper case letters. Now I noticed that there is also precedence for the latter case. Sorry for wasting time with this, I'll merge...