-The -root option is used by developers integrating this with automake
-tools or packaging tools that require a prefix directory to be
-specified. The root represents the "libdir" component of a prefix
-(typically prefix/lib).
+The -root option is used to specify the "libdir" value of an installation
+prefix which differs from the prefix of the system GAC.
+Typical automake usage is "-root $(DESTDIR)$(prefix)/lib".
+To access assemblies installed to a prefix other than the mono prefix,
+it is necessary to set the MONO_GAC_PREFIX environment variable.