Since there is so much overlap between the Dolby A and Dobly SR articles, should they be combined in a single Dobly Stereo article?
Also, while it does not relate to the sound format per se, I would suggest mentioning the use of a low pass filter to divert the low frequencies to a sub in addition to the 4 encoded channels. Dolby started designing their sound processors to do this pretty early on, so they intended both A and SR to play in 4.1.