Specifies the logical boxing (packaging) of mathematical element. For example, a boxed object can serve as an operator emulator with or without an alignment point, serve as a line break point, or be grouped such as not to allow line breaks within. For example, the \"==\" operator should be boxed to prevent line breaks....often used when one or more glyphs combine to form an operator...often used when one or more glyphs combine to form an operator...