READ (or RETURN) with the INTO phrase might be performed using a different record description if the file contains multiple record descriptions and not all of the record descriptions are alphanumeric.
A file will be affected only when it is fixed format, there are multiple 01 record descriptions, and at least one of the record descriptions is a numeric or numeric-edited item.
When deciding which record description to use as the sending field for an implicit MOVE statement, the compiler selects the longest of the 01 record descriptions. If multiple record descriptions have the same length, then the first such record description is chosen. This is true under both CMPR2 and NOCMPR2. However, the method for determining which 01 record description is the longest is different.