README.txt

These are MySQL, Firebird and Postgre data layers for YetAnotherForum. MySql data layer should be completely upgradable from YAF previous versions. Report bugs if there will be problems. 
Simply replace corresponding files. Details are in manual. It's a bit outdated but I'll sync it when I have time.
Current version is for 1.9.6.1. Previous versions are usually branched. Look for tags and branches.