NAMSTRSUBSCHARG, Subscript #nnnn with value vvvv in name specification specifies a $C/$ZCH with number cccc that is invalid in the current $zchset
GDE Error: This indicates that the nnnn'th subscript in a name specifies a string subscript using $CHAR/$ZCHAR but one of the arguments to this function (potentially in a comma-separated list) is invalid.
Action: An invalid integer argument is one which returns a null string when passed to $CHAR/$ZCHAR with the current $zchset setting. Specify the string subscript with a valid argument to $CHAR/$ZCHAR.
