Live music collecting has always been something that requires a lot of time and/or resources. Obtaining live performances is not as easy as going down to your local discount center. Obtaining shows has always involved networking with other people. This is often a positive experience but problems exist.
In the days of vinyl bootlegs (when only a small part of Led Zeppelin's live catalogue was covered), the only way to purchase a concert was to get a copy of the show from the master tape. That caused many generations of the same recording but due to amateur, poor techniques of copying the quality of most copies was far away worse than original one and the copies also very often occurred by tape noise, cuts and distortions. Only a very small amount of the original master tapes are survived. Most of them have been lost or destroyed accidentally and high generation copies are the only remainders of those glory days.
No doubt in the tape trading days every copy meant some sound quality loss. The digital cloned copies of modern times are far removed from the hissy cassette days. The tape trading days involved a smaller group of die hard collectors. Need to say that the people were of a higher standard in the collecting circles, but that is a different subject.
The CD-R trading days have been one of great highs and great lows. CD-R burner's have meant that it's possible to obtain a CD-R that can sound as good ten copies later as the original sounded. Unfortunately too many people had no idea how to copy discs correctly and that often introduced copies with a lot of digital errors such as gaps, dropouts, static, pops, etc. This problem seems to disappear completely when we talk about free sharing of audio and video recordings through dedicated servers as well as through private trade. Even with little advancement in current technology, collectors now have a unique opportunity to obtain and share recordings through free torrents, which require absolutely minimal knowledge and are by definition free from errors that were the nightmare of trade times by physical media.
Below this is my own attempt to present a list of tapes - often called as low gens - known to exist in a chronological order. When I listed the tape, I based it on its generation and original length. The things such as edits, cuts or difference in quality are mostly attributed to each of the tape listed but sometimes this information still needs to be supplemented due to lack of sufficient information. Additionally, some tapes vary between themselves being the same generation or evena a copy. This is especially true when the same tape is transferred again and the person responsible for it makes unexpected manipulations in the form of editing fragments that do not contain music or many other actions that may affect the final character of the recording.