CALL ON is just a synonym for SIGNAL ON

[RossPatterson]

The CALL ON support just a synonym for SIGNAL ON. For example, the code in compile.c says:

/* ///////// NOT CORRECT //////////// */
/* Make it work as the SIGNAL ON ...  */
    if (!CMP("OFF") || (!CMP("ON"))) {
        C_signal();
        return;
    }
/* ///////////////////////////////// */

which is certainly the right comment and wrong code, as CALL ON and SIGNAL ON work very differently.

This is an original issue in bREXX, so try to fix it in a way that CMS, MVS, and the ur-bREXX can all benefit from the update.