An obsolete keyword was detected.

#2503   Compile-time warning

An obsolete keyword was detected.

Additional Information

The keyword sequence 'X' is deprecated; use 'Y' instead.
    where X is the form supported in older versions of the language, Y the recommended form.

Explanation

Obsolete forms of the language include the verbose comparison operators (such as using 'IS EQUAL' instead of '='), '=' for pattern-assignment instead of '=>', and the names SGML and OUTPUT instead of #MARKUP-PARSER and #CURRENT-OUTPUT. Such forms are subject to eventual removal from the language.