A CASE clause of the current DO SELECT-TYPE block refers to a type that is not a sub-type of the head type.
#2191 Compile-time error
A CASE clause of the current DO SELECT-TYPE block refers to a type that is not a sub-type of the head type.
Additional Information
'X' is not a sub-type of 'Y'.
Explanation
All types referenced in case clauses of do select-type must be subtypes of the static type of the expression
following do select-type, i.e., the head type.