When using my studio (studio one) to tune my guitar,there are 4 or 5 different tuning's,I use iso440.Anyhow,when tuning in drop D sharp D#,there are small numbers that appear next to the note,.For instance I tune to D# on low E and comes up D#2,(but the 2 is much smaller then the one in this sentence),or tuning high E comes out D#3.What do these small numbers mean showing up at end of note? They can range from 1 to 5,so far from what I see.
It sounds like those are octave designations. Middle C on a piano is either C3 or C4, depending on who you ask. If you play a chromatic scale to test, you should see the numbers break between B and C.