Operations can be performed on objects in the QOPT file system through either the integrated file system interface or APIs provided by a hierarchical file system (HFS).
Whereas the integrated file system is based on the Integrated Language Environment® (ILE) program model, HFS is based on the original iSeries™ server program model.
The HFS APIs allow you to perform a few additional operations that the integrated file system does not support. In particular, you can use HFS APIs to access and change directory extended attributes (also called directory entry attributes) or to work with held optical files. Be aware that the naming rules for using HFS APIs are different from the naming rules for APIs using the integrated file system interface.
For more information about HFS APIs, see the
publication Optical device programming 
.