Retro1.org codex

&LENGTH FUNCTION                                         EXEC built-in function

Use the &LENGTH function to determine the number of characters in a token.  The
format of the &LENGTH function is:
+-----------+-----------------------------------------------------------------+
| &LENGTH   | token                                                           |
+-----------+-----------------------------------------------------------------+
where:

token    specifies the target token that is to be examined for nonblank
         characters.  The result of the &LENGTH function is the number of
         nonblank characters in the specified token.  This function is valid
         only on the right-hand side of an assignment statement.  For example:
            &LEN = &LENGTH ALPHA
            &TYPE &LEN
         results in the display:
            5