Channel order in OpenCV

I have been reading in a few forums that OpenCV has the BGR channel order by default.

It is also possible that a cv::Mat may have RGB channel order.

A gray conversion would specify CV_BGR2GRAY or CV_RGB2GRAY as a parameter.

1) Are there any other options, than RGB and BGR ?

2) Is there any way to find out - through code - what the order of channels is ?

Thank you.