In the thread:

"marginal notes have been partially cut off by the ancient binder."
http://www.purebibleforum.com/showthread.php?t=224

Posts 4,5,8 and 9


We find evidence that Tischendorf originally found, and was working with, a larger manuscript. And that he trimmed that ms, eliminating some notes. So far, none of the writers in the 150 years of Sinaiticus science (Tommy Wasserman) has made a comment on what appears to be a rather incredible mangling of the ms.

We also see that margin notes were a point of contention between Simonides and Tischendorf. Tischendorf berated Simonides for his mention of margin notes .. yet he apparently cut them off.