Table 16 – Additional entries specific to an object stream dictionary

key

type

description

Type

name

(Required) The type of PDF object that this dictionary describes; shall be ObjStm for an object stream.

N

integer

(Required) The number of indirect objects stored in the stream.

First

integer

(Required) The byte offset in the decoded stream of the first compressed object.

Extends

stream

(Optional) A reference to another object stream, of which the current object stream shall be considered an extension. Both streams are considered part of a collection of object streams (see below). A given collection consists of a set of streams whose Extends links form a directed acyclic graph.