Overview

An index block (regular or alias) is a 4KB block whose overview is composed of these parts:

Header
Table of index entries.
Sequence set chain pointer entry. For level-1 index blocks only. Follows last index entry.
X'0C' Delimiter
(At end of block) Table of two-byte offsets to the index entries.

Figure 1 is an example of an overview of a level-1 index block. The first 14 bytes is the header. In this example, n (in the header) is the number of index entries. Offset X'0EF8' is the sequence set chain pointer entry (which follows the last index entry). This offset value is also found in the header.

Figure 1. Example Overview of a Level-1 Index Block A graphical representation of a level-1 index block.