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HELP ISCONSTANT Jonathan Laventhol, August 1984. POP11 programs can have variables (see *VARS) and constants (see *CONSTANT). Sometimes it is useful to be able to find out if some word has been declared as a constant, and you can do so like this: isconstant("isconstant") => ** <true> Constants can only be assigned to once. Given a "fresh" constant which has not yet been assigned to, this procedure returns the word "undef". It returns true for a constant which has been given a value, and false for anything else. See *ISASSIGNABLE