Resolution:
Correct the code; then recompile.
Example:
In the following example, both the IMPLICIT and EXPLICIT operands use STRING as both the source and target type.
class-id A. operator-id implicit (param1 as type A) returning ret as string. set ret to param1::ToString end operator. operator-id explicit (param1 as type A) returning ret as string. set ret to param1::ToString end operator. end class.