CMPWG Oct-1-2015:

The description of the OptionSet and the parameters is very confusing. The relationship between the "Value" and "ValidBits" is not articulated well. We could not understand the relationship until it was described to us.

The description of the "Value" property does not describe WHY Bytes are used. It was later explained that this was to keep the bitmask in 8-bit blocks so even strange-sized values could be easily sent over the wire.

The "ValidBits" property seems very, very similar to a Subnet mask in an IP address. This might simple comparison would help the reader.

I've created a graphic (PPTX) with a 10-bit bitmask example that I hope will help.