The number of object types is huge and a small subset of them are available to users.
The human readable form of the object type is always a three to six character mnemonic preceded by an asterisk.
Generally speaking all libraries created by IBM for use by the operating system begin with the letter 'Q'.
IBM Standard Libraries: A library list (*LIBL) is an object which specifies a default set of locations to look for an object (similar to the PATH mechanism of other operating systems).
Some job descriptions specify the special value *SYSVAL which means that the library list can be found in the system value QUSRLIBL.