Update: documentation cleanups, fix observed problems, retun F_data_not without error bit

Update: documentation cleanups, fix observed problems, retun F_data_not without error bit

Organize the return codes.
Fix any probles in the commend documentation that I happened to notice.
This is not complete, there will be follow up commits to address more cleanups.

I noticed that there were some public directory functions incorrectly have 'private_' in their name.

The conversion functions should no longer consider no data an error.
Just report that there was nothing to do.