Regedit file format
I would like to document the file format of regedit utility, so data can be merged into the registry.
From the command-line you can (silently) merge data from a batch file like this:
regedit /s file.reg
Exporting from a subkey goes like this:
regedit /e file.reg "HKEY_XX\key"
Remove keys and values by using the minus sign (-).
REGEDIT4 [-HKEY_CURRENT_USER\RemoveThisTree] [HKEY_CURRENT_USER\RemoveValue] "valueName"=-
Minus sign to delete mentioned here: MSKB310516: How to add, modify, or delete registry subkeys and values by using a .reg file (Archived here.)
Documenting the .reg file format is really more Microsoft's job.