What's Adjunct Proceedings? I came across a paper today: 


  Plink It: Paper-Based Links for Cross-Media Information Space Jurgen
  Steimle, Nadir Weibel, Simon Olberding, Max Muhlhauser, and James D.
  Hollan. Adjunct Proceedings of ACM Symposium on User Interface
  Software and Technology, 1969-1974, 2011. (PDF)


I am curious: what does Adjunct Proceedings mean? The paper's style and format looks quite different from Computer Science papers that I used to read. Could anyone explain this to me?
Large conferences have "main tracks" where the normal papers are received, peer-reviewed and published/discussed in the traditional format. In these conferences there is more and more often the tendency to provide researchers to write "cutting edge" research, that should not undergo the formal peer-review process, or simply the acceptance rate has a clearly lower bar than the normal tracks of the conference. This second type of papers will be published in the "adjunct proceedings".

One would then have two sets of proceedings, one where the normal papers are, and the other one where more experimental papers are. This separation has got a reason: the program committee of a conference wants to keep the two types of papers separated, since the papers in the normal proceedings will be cited more often than the ones in the adjunct proceedings