These documents describe various parts of ZODB. There are two documents to note:

ZODB/ZEO Programming Guide
PDF: zodb.pdf HTML: zodb/zodb.html
ZODB Storage API
PDF: storage.pdf HTML: storage/storage.html

The documents located here can be formatted using the mkhowto script which is part of the Python documentation tools. The recommended use of this script is to create a symlink from some handy bin/ directory to the script, located in Doc/tools/mkhowto in the Python source distribution; that script will locate the various support files it needs appropriately.

The Makefile contains the commands to produce both the PDF and HTML versions of the documents.