Contains the apMatch token, followed by an AttrParse token.
apMatch. Contains the token to match to determine whether the optional section is present. apMatch is a subtoken that can be used only within the opt token. apMatch token always contains the flag token as a subtoken.
AttrParse. Specifies how to parse the optional part of the screen. This version of the AttrParse element does not use the name argument. It can contain any other token.