To globally define the same name more than once, use this directive to undefine the name before redefining it. If you do not undefine the global name before redefining it, the compiler produces a warning message for non-globally (scoped) defined names. For globally defined names, &UNDEFINE is optional, but recommended for code readability. If &UNDEFINE is not used, the last &GLOBAL-DEFINE statement is used.