Since match structures (Section 8.3.2) will contain data from many images, potentially on different dates, match structure file names will not contain either the date field or the index number. The rest of the name (such as ``ghu0003_3a'' or ``sky0350-0148_3a'') is called the ``root'' name, and so the match structure file will be named either ``ghu0003_3a_match.fit'' or ``ghu0003_3a_relmat.fit'', depending on whether or not the relative photometry procedure (Section 8.3.3) has been applied to it.