GDF -- Can anyone suggest some good reading?

GDF is the European Union Geographic Data File standard for transport systems.

References for GDF - Geographic Data Files

1. ISO 14825:2004 - Intelligent transport systems -- Geographic Data Files (GDF) -- Overall data specification
2. This page has 'Documentation and Manual' for GDF 3.0 with examples, information on how to specify a GDF Map, GDF and location georeferencing and several reference materials in the form of PDF Documents.
3. Specification of the GDF format and a sample GDF file
4. Usage of Data in this format is supported by leading Data Interoperability software FME. Here is the page.