The maximum length of a based VARYING or VARYINGZ string must be equal to the maximum length of any string upon which the based VARYING or VARYINGZ string is overlaid. For example:
declare A char(50) varying based(Q),
B char(50) varying;
Q=addr(B);A based VARYING string can only be overlaid on a VARYING string; a based VARYINGZ string can only be overlaid on a VARYINGZ string.