OF OCTAL OFF
OF .. ENDOF ( comp-value case-value -- comp-value )  
smart-word ansi .6.2.1950 <CORE>
compare the case-value placed lately with the comp-value being available since CASE - if they are equal run the following code-portion up to ENDOF after which the case-construct ends at the next ENDCASE

reference: p4_of in ../src/core.c:2294, export CS OF