+ifdef INDICES
+# We need to be able to build the index source files without involving
+# the main $(PN).pdf rule, in order to avoid a chicken-and-egg problem.
+# This is similar to the $(PN).aux rule above, except that an index is
+# optional and there might be more than one of them.
+$(INDEX_SRCS): $(PN).tex
+ $(LATEX) $(PN).tex
+endif
+
+ifdef INDICES
+# Create real indices from source files by running "makeindex" on
+# them. We depend on SRCS here because we *do* want to rebuild the
+# index if the source document changes, but we use an order-only
+# dependency (see the bbl rule below) on the idx files to prevent us
+# from going into a rebuild loop when the idx files are regenerated.
+%.ind: $(SRCS) | %.idx
+ makeindex $|
+endif
+