Create MXD files that are compatible with a previous version of ArcMap

Summary

ArcMap can save an MXD file that can be opened with a previous version of ArcMap.

Procedure

Instructions provided describe how to save MXD files in a format compatible with earlier versions of ArcGIS.
For example:

1. Click File > Save A Copy.
2. In the Save as type drop-down menu, select the compatible ArcMap version, for example ArcMap 10.6 Document (*.mxd).
3. Browse to an appropriate file location and type a filename.
4. Click Save.