Authority Control:

One of EAD's strengths, and a reason for its widespread acceptance, is that it is relatively flexible. More than most other schemas, EAD lets for variety in detail of coding, sequence, and quanity of information. The LEVEL attribute can be entered high up on the hierarchy or low down on it. This flexibilty of course does not mean that EAD is standards free. It wouldn't be a proper metadata scheme without standards. The all-important XML tags vary not at all.

EAD is maintained by the Society of American Archivists, the Research Libraries Group, and the Library of Congress.

The SAA is more involved with actually talking to archivists at workshops, its role may be smaller than the roles played by RLG and the LOC.

The RLG manages the EAD Best Practices Manual, this is scripture for those who wish to make universally recognized EAD. The EAD Application Guidelines provide indispensable information about the tags that EAD runs on.

The LOC is the official master of EAD.

http://www.loc.gov/ead/

It is the LOC that maintains the databases of the EAD tags.

Overall, while EAD tags are standardized, the EAD hierarchy is not. Different archivists may use the tags in slightly different places in the XML hierarchy.