What does the double-dash [--] option do on git reset?

Question

I've seen commands like:

git reset e542 -- readme.txt

I understand this command puts in the index the contents of the file readme.txt from commit e542. But what's the -- option doing there?

The git reset man page lists it as optional for the first two forms but I couldn't find what it means.

git reset [-q] [<commit>] [--] <paths>…
git reset (--patch | -p) [<commit>] [--] [<paths>…]

Answer 1

-- separates branch names from file names, in case there is any ambiguity (if you have a branch and a file with the same name). If there are no ambiguities, you don't need the --.

Also as mentioned by Jonas Wielicki, this allows for file names that start with a -; these would otherwise be interpreted as command-line options.