-Some versions of the patch program let the user specify `-b backup-extension'.
-Other versions only permit `-b', which (usually) assumes the extension `.orig'.
-Yet others force you to use `-z<backup-extension>'.
+Some versions of the patch program let the user specify @option{-b
+@var{extension}} to specify a backup file name extension. Other
+versions only permit @option{-b}, which (usually) assumes the
+extension @file{.orig}. Yet others force you to use
+@option{-z@var{extension}}.