The principle was straightforward. Someone had a recording they were willing to distribute and the tree was the structure through which it was done. The recording itself was the seed and whoever made the first set of copies was the trunk. From there you went to branches and leaves.
As a rule, each tree was a separate project, with its own structure, but there were permanent versions, where the structure remained in place and someone provided a new seed from time to time.
The first one I encountered was the Mushroom Express, which distributed a couple of Allman Brothers or Allman-related shows every couple of months, and the idea was one that I borrowed for what became one of the most surreal little episodes in my life as a music fan.
It probably comes as no surprise to learn there was a deal of discussion covering these issues in on-line forums, and most people would have been aware of a particular artist’s views on the matter of unofficial recordings. In many cases, the artist was open and up front on the issue, so everyone knew where they stood. If they didn’t condone the practice I tried to stay away from the illicit recordings - not always possible, of course - but where artists were taper friendly there was no secret about it.
Getting your hands on the recordings was not, however, always straightforward.
The Little Feat Hoy Hoy mailing list might not have been the first such entity I subscribed to, but it was one of the first few, and it was soon obvious that Little Feat were taper friendly and, moreover, Bill Payne and Paul Barrere from the band posted intermittently on the mailing list.
On other lists (the Neil Young Rust list was an example) there were frequent posts offering shows for trade or B&P, announcing new trees, or otherwise related to such matters. On Hoy Hoy, however, the offers were few and far between.