-x [--extensions] ARG    : Default: '-u'. When Subversion is invoking an
                             external diff program, ARG is simply passed along
                             to the program. But when Subversion is using its
                             default internal diff implementation, or when
                             Subversion is displaying blame annotations, ARG
                             could be any of the following:
                                -u (--unified):
                                   Output 3 lines of unified context.
                                -b (--ignore-space-change):
--