The constants below are defined by this extension, and
will only be available when the extension has either
been compiled into PHP or dynamically loaded at runtime.
This flag indicates that xdiff_[string|file]_patch functions should create result by
applying patch to original content thus creating newer version of file. This is the default
mode of operation.
This flag indicated that xdiff_[string|file]_patch functions should create result by
reversing patch changed from newer content thus creating original version.