This is a sketchy outline of the planned book contents:

Cover (Front page, text license...)
Index
Introduction
  Hierarchical code overview
  The life-span of a survey
Code issues before and during start-up of the system
  installer.pl
  survey.conf
  startup.pl
Request phase, session and arguments
  Handler.pm
  Argument.pm
  Session.pm
  Authentication.pm
Parser and document
  Document.pm
  System.pm
  Object.pm and common tag structure
Display
  Display.pm
  Multipaging
Data
  Submit.pm
  Data.pm
  DataEntry.pm
  The export modules
Misc and deprecated modules
  Admin.pm
  Statistics.pm
Presentations
Internationalizations
  Good and bad with PGetText
  The language files
How-To and checklists for common programming tasks
  Adding a parameter to a tag
  Adding a completely new tag
  Writing a new data export
  Making sure new modules get installed
  Adding new dynamic-content markup
  Writing a translation
  Compiling a modified translation file
Commiting code for fame and glory
  Code style and recommendations
  Keeping up-to-date with CVS
  Making a patch
  Sending in a patch for merging
  Getting CVS write access
  Writing documentation