In masechet Chullin, 19b, the gemara introduces an anecdote with the following (10th line down here) statement:
(סימן בכ"ד)
There is one side note saying that this was (is?) erased but I'm not sure that that answers my question. This mnemonic is explained (in the Steinzaltz as linked above, and in the Artscroll 19b1 note 6) as referring to elements of the names of the 3 amora'im who are now being quoted, R. ABa, R. Kahana and R. YehuDah.
But the gemara is rife with statements said in the name of long strings of rabbis and yet they don't all have preceding mnemonics to help anyone remember the source. On 19a there are lists of names when considering who might have authored a variety of opinions and none has a mnemonic. Whether this is a printer's addition to help during typesetting, or an ancient device to hep those memorizing text, why would it be inserted in only this case and not in every case where a long list of names is likely to be confusing?
