CAD tip # 11970:

For this, you can use either the specialized functions available in AutoCAD Map 3D and Civil 3D, or - sice version 2015 - also a plain AutoCAD and its function GEOGRAPHICLOCATION. If you need to find out, which coordinate system is currently assigned, you can detect it directly in the CAD application's status bar:

This option in the status bar can be enabled in Civil/Map through the command MAPSTATUSBAR with its option Show/Hide. And in AutoCAD through the setting "GIS coordinates" in the hamburger menu "Customize" in the right down corner. This setting is stored in the Registry in HKCU\Software\Autodesk\AutoCAD\R23.0\ACAD-2001:409\Profiles\PROFILENAME\StatusBar\Application\GeoCoordSys (1/0).

Another option for displaying the current coord.system (CS) is the dialog of the mapping command ADESETCRDSYS (N/A in plain AutoCAD):

Under the button "Select Coordinate System" (or through the command MAPCASSIGN) you can find the EPSG code of a given system - search for the name of the CS from the first dialog box:

The next method of listing the name of the current coordinate system is the LISP function in the mapping versions of AutoCAD:

(setq cscode (ade_projgetwscode))

A similar function can be achieved (and also in plain AutoCAD) using the variable CGEOCS. You can also display its content in a dynamic text Field.