There really isn't all that much redacted, though it's annoying. The redaction is heavy in the first 15 pages because there are a lot of reference to specific people, docket numbers, etc. I bet a lot of the "Certification <redacted>" you see are things like "Certification of John P. Spymaster." The other thing that gets redacted is the capabilities/limitations of the equipment. But the meat of the legal analysis is there (read past page 15).

To be honest they redacted only some names, the names of the isps they are working with, some numbers, and the names of certifications. Certainly there's some really interesting stuff here left non-redacted.

homework assignment, using the same typeface find valid strings (names of ISPs etc) that fit within the redacted blocks. Extra credit for using an NLP toolkit to ensure grammatical correctness, double extra credit for using the same grammar rules as the document.

It's not hard to guess honestly, especially with Quest getting those NSLs and the ceo getting fired, and ATT "secret rooms". They redacted them for legal reasons so companies can't sue ATT/Quest/etc. for "federally documented proof of violation of privacy contracts." Though that would be hilarious if it happened.

Haven't these companies already received retroactive immunity by act of Congress?

That may be true; another reason that they might be redacted is the "national security concern" of people (aka terrorists) avoiding those ISPs.

i agree, it's just frustrating to have to hop through them. and even though you're probably right, without actually seeing what is redacted, we will never know if that's all that they redacted.