APIs retrieve information from internal system objects.
Some of the information contains special values. For example, the list object API returns the object type as a special value (*PGM, *LIB, and so on). However, special values may be added in future releases. Even numeric values may have new special values. When you code to APIs, you should assume that the format of the information returned will not change from release to release, but the content of the information might change.