NAVD 1988 Missing from Vertical Coordinate System

[StormwaterAdmin]

I am trying to choose the output coordinate system in a project Z tool, but when I open the Vertical Coordinate System drop down I only see Ellipsoidal-based, Gravity-based, and Unknown Height Systems as options. The instructions I am following from several sources all show that there should be a "North America" drop down where I can then select NAVD88. I am unable to find that coordinate system even when typing it into the search box. Is there any way I can fix this?

[RhettZufelt]

If I put NAVD88 in the search box, it finds them:

R_

[StormwaterAdmin]

Thanks for the response! However, I don't want the "gravity-related" one. There should be an option to go Vertical Coordinate System > North America > NAVD 1988 based on the instructions I have been following for my workflow . Also, those ones include "depth" or "height" after them, but I just need the NAVD88.

[RhettZufelt · Accepted solution]

Sorry, thought all the NAVD888 were gravity related, at least that what ESRI docs show.

Maybe try searching for NAVD_1988 (or 5703 works also).

Can't find any real documentation on the difference except that Depth is positive going down, height is positive going up.

There may be differences, but sure doesn't seem to be documented very well, or, at least hard to find if it is.

Maybe someone at ESRI can chime in and clarify?

R_