What are the numbers associated with the Dropper Tool

[tomkinsrichard]

When I pause the Dropper Tool over a pixel in an image, a dialog box display numbers.

What do the various numbers mean?
In the example, the image is a 48 bit TIFF.
I see, R, G, B, O, and I guess that these are Red, Green and Blue, what is O?
Beside each, there is a colon followed by a number, 0, which would be 0 brightness? Next to that number, in brackets is (89), what is this number?
O has 255 and in brackets (65535) and at the bottom of the dialog it says, 100%.

I have been unable to find a reference somewhere that tells me what all these displayed numbers represent. I would appreciate it if someone could fill me in.

Thank you

[LeviFiction]

O is for opacity.

The percentage I believe corresponds to the opacity value as well.

The numbers in parentheses gives the 16-bit value represented by the RGB values...I'm guessing. It only shows up when you use a bit value higher than 8.