6.28 From my home group I issued CHGROUP GROUPA, and then issued a BUILD FILENAME;TEMP. A little later I CHGROUPed back to the home group and then tried to access the temp file, but to no avail. I couldn't even see it when I issued LISTFTEMP@,2. Where did it go and how do I find it?

It did not go anywhere. You did a CHGROUP to GROUPA before building the file. That is were it resides. LISTFTEMP@.GROUPA,2 will show it.