e optional features,
which typically involve more porting effort.
<P>
Note that the collector makes heavy use of <TT>ifdef</tt>s.  Unlike
some other software projects, we have concluded repeatedly that this is preferable
to system dependent files, with code duplicated between the files.
However, to keep this manageable, we do strongly believe in indenting
<TT>ifdef</tt>s correctly (for historical reasons usually without the leading
sharp sign).  (Separate source files are of course fine if they don't result