FTAM/9000 Programmer's Guide

Chapter 1 41
HP FTAM/9000 Overview
Overview of FTAM Concepts
FTAM File Structure Model
The FTAM file model consists of a hierarchical structure (ordered tree)
containing various levels.
• Each node in the tree contains a node descriptor. Node descriptors
reference specific parts of a file. However, a node descriptor may be
empty.
• Each node in the tree contains a data unit (DU). This data unit
contains the actual file contents.
A file access data unit (FADU) is the smallest unit you can access in
an FTAM file. A FADU is the complete information content of a subtree
(i.e., node descriptors and data units). FADUs may be nested and may
contain several data units.
The two file structures described by the Unstructured and Sequential
Flat constraint sets are identified in the following illustrations.
• An Unstructured constraint set contains one FADU consisting of one
node descriptor and one data unit.
Figure 1-5 FADU Defined by Unstructured Constraint Set
Root FADU
Node
Desc.
DU