What are the available options for Eloquent's Model::save() method?

Eloquent has a method called save(), which takes an optional array of parameters (options). However, the API reference doesn't seem to explain what these options are.

Is there a list somewhere that I'm missing? I could track them down through the source code of course (I see touch and timestamp, at least), but I figured at the very least this question would be useful as a reference to others.

via Chebli Mohamed