Determines the last time a file attribute of a physical file, such as FILENAME or FILEKIND, was explicitly modified, such as setting the attribute programmatically or by using the WFL ALTER statement. When copying a file to disk, library maintenance sets ATTMODIFYDATE to the current date if the user includes a FAMILYINDEX = <number> specification for that destination disk. Refer to the File Attributes Programming Reference Manual for a description of the ATTMODIFYDATE file attribute.