There really wasn't much compiled into CEF, it was a good idea that didn't catch on until .net arrived.
The cab here might be CEF from the look of it
https://www.hpcfactor.com/downloads/details.asp?r={620EBF94-443C-473...
https://krsuncom.tistory.com/entry/Windows-CE-Developers-FAQ
Quote
Common Executable Format (CEF)
One of the downsides to writing Windows CE applications in the past was the number of different microprocessors that needed to be supported, such as MIPS and SH3. Starting with Pocket PC, Windows CE devices now support a processor-neutral machine code set called Common Executable Format, or CEF (pronounced "keff"). You can compile into CEF using eMbedded Visual C++ and then run that single executable on any platform that supports CEF, such as PocketPC.
CEF-enabled platforms have a translator that takes the CEF code and translates it into the native code, such as MIPS or SH3. Translation can take place every time the application is run, or the converted code can be saved. There is an overhead in performance CEF applications run at around 80 percent the speed of native applications.
I'm not aware of any documentation on the instruction set