Villarino,
WELCOME TO THE AWS WELDING FORUM!!
The newest edition of API 1104 is the 21st edition and I believe it came out in 2013 and is just now getting pretty well adopted into every jurisdiction's update for codes and specifications (in this case, pronounced: suggestions).
It and the 20th edition are what are accepted as the open code book for the exam for AWS/CWI if you opt for the API exam instead of one of the AWS D1.X codes.
He Is In Control, Have a Great Day, Brent