The TO_PLS_INTEGER Built-in, which converts character strings to PL/SQL integers, is obsolete in versions after V1. The conversion utility replaces TO_PLS_INTEGER with the Built-in TO_NUMBER.
If you do not replace the TO_PLS_INTEGER Built-in, this compiler error is generated:
ERROR 201: Identified TO_PLS_INTEGER must be declared
Note: Other obsolete Built-ins must be replaced manually.
The conversion utility converts this PL/SQL V1 code:
PROCEDURE foo IS
v INTEGER;
BEGIN
v := TO_PLS_INTEGER(24);
END;
. . .to this:
PROCEDURE foo IS
v INTEGER;
BEGIN
v := TO_NUMBER(24); TO_PLS_INTEGER replaced with TO_NUMBER
END;