File Formats Blog

Section 3.6.2 of Adobe's PDF Reference, Version 1.6, tells us the following:

The tree contains nodes of two types -- intermediate nodes, called page tree nodes, and leaf nodes, called page objects -- whose form is described in the sections below. Applications should be prepared to handle any form of tree structure built of such nodes. The simplest structure would consist of a single page tree node that references all of the document’s page objects directly.

There's a subtle inconsistency here. Before Acrobat 7, it apparently was true that the simplest page tree structure had a page tree node at the root. But Acrobat 7 can create a page tree node that consists of just a single page object node. Applications which are prepared to handle "any form of tree structure built of such nodes" should indeed handle this, even though it contradicts the ensuing statement about what the "simplest structure" is.

On such details do programmers stumble and fall. Sigh.

# posted by Gary McGath @ 1:40 PM 0 comments