If you extract NGS datasheets from this point on, you will notice that the published GEOID HEIGHT will be listed as developed through GEOID12B, rather than the previous GEOID12A. Do not be concerned about this, as both models are exactly the same for the Continuous 48 . Here is the note that the NGS Geoid Team provided to us concerning the new model.
“NGS has produced a new geoid model, GEOID12B, to replace the previous GEOID12A model. GEOID12B is identical to GEOID12A everywhere, except in Puerto Rico and the Virgin islands, and it supersedes models GEOID12 and GEOID12A.”