32 or 64 

187} Is the batch file called on a 32-bit or 64-bit system?

Originally the question was "Is batch file called from 32-bit or 64- bit cmd.exe?" There is a lengthy, slightly diverging discussion about the original subject in the reference at the end of this item. The solution to the essential modified question, however, is straight-forward.
alternatively Since some batches use auxiliary executable programs, such batches will not work in a 64-bit environment if the said executables are 16-bit. At least 32-bit is required. Hence the need of a simple test. Consequently, you might have something like this:
More fully, what kind of OS version compatibility tests depends on the particular contents of the script file. What kind of commands and maybe auxiliary programs it uses. Two examples. 1) If one utilizes sed.exe and/or gawk.exe, very useful UNIX ports, their 16-bit versions will not run on a 64-system. 2) If one uses C:\Windows\System32\fsutil.exe in a post-XP command line script, one will run into addition complications with user privileges compared with running it on a pre-Windows 7 system. Therefore, one might want to test, not only for the bit flavor but also for the OS version. One might include something like this:

The the sake of the exercise, the latter could be written as a subroutine, such as: