Not ibid. but id. I expect —same author, different passage.
Smyth’s reference system is fairly transparent, and surely he provides a list of abbreviations? Same goes for the indispensable LSJ and its shorter (and older) incarnations. Space is always at a premium in such works, but I think you’ll come to appreciate the neatness.
In the Russian orthography used before 1917, every word ending in a consonant had a sign added, ь or ъ, to show whether the consonant was palatalized or not. Then they dropped the final ъ and let the absence of a sign show that the consonant was not palatalized.
The story is that the change made War and Peace shorter by ten pages.