Brown’s Gas is common ducted oxyhydrogen.

Therefore Brown’s Gas entails:

1: The production of an oxyhydrogen gas

2: The design of the electrolyzer

The terminology oxyhydrogen refers to a gas alone, and does not entail a production method. Since oxyhydrogen can be produced in an independently ducted electrolyzer, or from botted gases, there are two distinct methods of production. Brown’s Gas is only specified to be produced in a “common ducted” electrolyzer, having only a single production method.