>>-TRACE(--+--------+--)---------------------------------------><
           '-option-'      

returns trace actions currently in effect and, optionally, alters the setting.

If you specify option, it selects the trace setting. It must be one of the valid prefixes ? or ! or one of the alphabetic character options associated with the TRACE instruction (that is, starting with A, C, E, F, I, L, N, O, R, or S) or both. (See Alphabetic character (word) options for full details.)

Unlike the TRACE instruction, the TRACE function alters the trace action even if interactive debug is active. Also unlike the TRACE instruction, option cannot be a number.

TRACE()       ->   '?R' /* maybe */
TRACE('O')    ->   '?R' /* also sets tracing off    */
TRACE('?I')   ->   'O'  /* now in interactive debug */