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AutoCAD Architecture is built on top of AutoCAD, and both use the same acad.exe file as the main program file. AutoCAD Architecture's features are contained in multiple runtime extension files (ARX).
Here are the target strings from two AutoCAD Architecture [ACA] shortcuts. The first runs ACA "as AutoCAD". Note that the profile referenced (after the /p switch), is the AutoCAD profile, and that there is no /ld switch. The second is from the ACA US Imperial profile. This sets the AutoCAD Architecture (US Imperial) profile current, and, more importantly, calls for the AecBase.dbx file to be loaded. This will cause AutoCAD to recognize the session as an ACA session, and things like the additional AEC tabs in the Options dialog will appear. The profiles also have an effect; the AutoCAD profile will use acad.cuix as the main customization file whereas the AutoCAD Architecture (US Imperial) profile will use the aca.cuix file as the main customization file. The example strings below are for the 2016 release.
"C:\Program Files\Autodesk\AutoCAD 2016\acad.exe" /p "AutoCAD" /product "ACA" /language "en-US"
"C:\Program Files\Autodesk\AutoCAD 2016\acad.exe" /ld "C:\Program Files\Autodesk\AutoCAD 2016\AecBase.dbx" /p "AutoCAD Architecture (US Imperial)" /product "ACA" /language "en-US"
David Koch
AutoCAD Architecture and Revit User
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