>>-.---.---.---CHECKREFMOD-.----------------.--.---><
   +-/-+   |               +--NOZEROLENGTH--+  |
           +-NOCHECKREFMOD---------------------+ 
               	 If no parameter is set, the effect is the same as CHECKREFMOD"NOZEROLENGTH", except that reference modifier lengths of zero are permitted at run time. However, if a reference modified length is known to be zero at compile time, an error is generated. This is equivalent to the effect on reference modified items of the directive SSRANGE"3".
| Default: | NOCHECKREFMOD | 
| Phase: | Check | 
| $SET: | Initial |