While creating the package, the SQL statements are checked to determine which release can support the function.
This release is set as the restore level of the package. For example, if the package contains a CREATE TABLE statement which adds a FOREIGN KEY constraint to the table, then the restore level of the package will be Version 3 Release 1, because FOREIGN KEY constraints were not supported before this release. TGTRLS message are suppressed when the TGTRLS parameter is *CURRENT.