GIS overview - General overview of GIS development. Road plans and overall architecture etc

GIS API - A list of API functions for other modules to access the GIS.

GIS Architecture - Diagram of the GIS's overall architecture

GIS Structure - A Description of the building blocks of the internal GIS as well as UML diagrams and descriptions of the database structure. (GSoC - GIS)

Module Integration Guide - A Guide to integrating the GIS into a module. (GSoC - GIS)