Why are the map units in Arc Pro read-only?

Question

I am working with archaeological data (specifically, a site map drawn in CAD) for a site whose real-world location is unknown. The site was excavated using an arbitrary grid with a datum of 0 easting and 0 northing. I know that the unit of measurement on the site was feet. Previously, I was able to work with similar files in ArcMap, where it was possible to work with CAD maps that did not have a defined coordinate system or projection and the map units could also be set to feet; however, this is not possible in Arc Pro for some reason: it seems the map units are read-only and set as meters and not feet.

My question: Is this a bug?

The file I'm working with will have no base map in the real-world. It is simply a site map in order to do intra-site analysis of map features using GIS.

Thanks for input!

LeslieCooper · Answer

Update: In case anyone is following this...

I did find a place where "Local" is an option.

If you go to the Map Properties menu >> Coordinate Systems >> Create New Projected Coordinate System,

there is an option for "Local" under the "Projection" field in the setting menu.

Maybe this helps someone else!

LeslieCooper · Answer

I have tried in vain to set the coordinate system to "local" as it states ON THE ARC PRO website:

Coordinate systems, projections, and transformations—Properties of maps | Documentation

"Horizontal coordinate systems can be of three types: geographic, projected, and local." It also provides a PDF entitled "ArcGIS 10.8.0 and ArcGIS Pro 2.5 Projected Coordinate System Tables" in which the following is the listing for something called "Local":

Alas, "Local" is not actually an option under Geographic, Projected, or a third option in ArcGIS Pro.

I'm guessing the reason is the same as stated above??

LeslieCooper · Answer

Thanks  for taking time to reply. That is unfortunate, indeed. Needless to say, I hope they decide to add that functionality as well!

Leslie