Abbr - abbreviated
Gk Ch - Greek Chant
Bulg - Bulgarian
Znam - Znamenny Chant

This list was probably drawn from the designations used in standard sources such as the Synodal Obikhod notnago peniia and Sputnik psalomshchika; I don't think that these are entirely reliable. The troparion melody of tone 4, for example: Myroslaw Antonowycz has grouped this with the Bulgarian chant as sung in Ukraine, and in fact, as his table shows, it is quite similar in particular to the Galician variant of the "Bulgarian" troparion melody. The same is true of tone 8; it may well be derived from the "Bulgarian" Chant, for it clearly resembles in this case the melody published by A. Nikolov. The stichera in general are simplified versions of the Kievan Chant or once or twice of the Lesser Znamennyi (which resemble each other); the prokimena of the Znamennyi Chant; and the troparia (except for Tone 5) of either the Greek Chant or the Bulgarian--it is not always easy to determine which. The Russian Greek Chant is often said to have come by way of Ukraine, like the Bulgarian, but I doubt this. So far, the melodies in old Ukrainian and Bielarussian irmologia that I have seen are not found in the Russian "Greek Chant".