-the ROOT and PREFIX variables specified in the Makefile -- e.g., you can
-use "make PREFIX=/opt/pciutils ROOT=/opt/pciutils install" to create
-a separate installation not interfering with the rest of your system.
+the PREFIX variable specified in the Makefile -- e.g., you can use
+"make PREFIX=/opt/pciutils install" to create a separate installation
+not interfering with the rest of your system. Setting the DESTDIR variable
+will allow you to install to a different directory from the one you intend
+to eventually run it from. This is useful for people who are packaging
+pciutils to install on other computers.
+
+The configure script will automatically enable support for a compressed
+pci.ids if you have zlib installed. You can override its guess by using
+"make ZLIB=no" or "make ZLIB=yes". If compressed support is enabled,
+pciutils will use pci.ids.gz in preference to pci.ids, even if the
+pci.ids file is newer. If the pci.ids.gz file is missing, it will use
+pci.ids instead.