Level 66 and managed code

We're converting some REALLY old mainframe code to VC 2.3 for VS 2013 and we are getting a COBCH1710 when a Level 66 data item is referenced in the Procedure Division, specifically as an operand in an IF statement. I've dug around in the product documentation and can't find anything that says Level 66 shouldn't be used in managed code, but I've missed stuff in the past. Does anyone know of a restriction of Level 66 data items in managed code?