Here some links to sites which has something to do with UN/EDIFACT. First of all, it's the UN itself - all of the stuff here is based on the data they provide.
- UN/EDIFACT Directories
United Nations Directories for Electronic Data Interchange for Administration, Commerce and Transport
- ISO 9735 (and more)
Electronic data interchange for administration, commerce and transport (EDIFACT) - Application level syntax rules