NUMBER? NOT OCTAL
NUMBER? ( addr -- d flag )  
<FORTH-83-L&P>
convert counted string to number - used in inner interpreter ( INTERPRET ), flags if conversion was successful 
 example:
   BL WORD  HERE NUMBER? 0= IF ." not a number " THEN .

reference: p4_number_question in ../src/lpf83.c:0336, export CO NUMBER?