A rule disallowed in modules has been encountered.
          #2156   Compile-time error
          A rule disallowed in modules has been encountered.
Additional Information
 The rule is 'X'.
Explanation
Certain rules and declarations are allowed only in the main
program. These are
process, break-width, no-default-io,
data-letters, declare #main-output has, declare #error has, declare #main-input has, declare #process-input has, declare #process-output has,
binary-input, binary-output, delimiter, and
symbol.