Sets the boundaries for a group. It is derived from a named EscapeE field
or, when there are no commas separating the values:
Alternatively, the boundaries may be supplied by the _PAGE and _PRINTABLE symbols, e.g.
Tip: a leading underscore is used to distinguish special symbols from user-defined fields. If there is no user-defined field with the same name then the underscore may omitted, e.g. BOUNDS="PRINTABLE".