-often needs to be told about header files to use,
-\ref{include file option}. Rather than maintaining the list of
-files the source depends on in a \tr{Makefile}, it is possible to
-do this directly in the source file using the \tr{OPTIONS} pragma
-\index{OPTIONS pragma}:
+often needs to be told about header files to use. Rather than
+maintaining the list of files the source depends on in a
+\tr{Makefile} (using \tr{-#include} option), it is possible to do this
+directly in the source file using the \tr{OPTIONS} pragma
+\index{OPTIONS pragma}: