After a call of pcre2_match() that was passed the match block that is
this functions argument, this function returns a pointer to the last (*MARK)
name that was encountered. The name is zero-terminated, and is within the
compiled pattern. If no (*MARK) name is available, NULL is returned. A (*MARK)
name may be available after a failed match or a partial match, as well as after
a successful one.
There is a complete description of the PCRE2 native API in the
page and a description of the POSIX API in the