I read this issue, but it did not answer the question.
I wanted to set "core.filemode" to false, as I share my repository with Windows and Linux (and other unix) boxes. Feeling rather clever and as though I'd learned something after researching my problem, I bravely issued:
git config --global core.filemode false
which, dutifully set the proper value in the global config file. Now, operating under the assumption that the global settings would form the basis for local settings, I cloned our central repository from Linux. Switching to Windows, I see that git thinks that all 16k files have been modified (thanks, filemode). Examining the local config file, shows that filemode is set to true (the global value is false, as I had issued the above command on both Windows and Linux prior to cloning).
Clearly, I had not learned enough.
So, my question is, where are the default settings that are dropped into the local config file stored and tuned?