-specified directory (or directories -- separate with colons). This is
-useful for multi-binary packages where a library is built in one
-package and another package contains binaries linked against said
-library. Relative paths will be made absolute for the benefit of
-dpkg-shlibdeps.
+specified directory (or directories -- separate with colons). With recent
+versions of dpkg-shlibdeps, this is mostly only useful for packages that
+build multiple flavors of the same library, or other situations where
+the library is installed into a directory not on the regular library search
+path.
+
+=item B<-L>I<package>, B<--libpackage=>I<package>
+
+With recent versions of dpkg-shlibdeps, this option is generally not
+needed, unless your package builds multiple flavors of the same library.
+
+It tells dpkg-shlibdeps (via its -S parameter) to look first in the package
+build directory for the specified package, when searching for libraries,
+symbol files, and shlibs files.