Deciphering the Musical Notes
Sayaka Miki's magic is based on music and includes its own musical notes based on common ones from real life. Many have been identified, but not all.
Deciphering Process
Sayaka's Spell Circle
Sayaka's notes were easily connected to musical notation in real life soon after their first appearance, but, like the Witch Characters, inconsistencies were soon found. For example, note heads were pointing to strange directions, Witch Character F symbols appearing above the staves, the complete lack of time signature and distinguishable bar lines, and rests of strange durations in strange places. These things lead to an assumption that the scores are mirrored or indeed just nonsense. Even though the definite order of all the musical symbols has been confirmed, a musical piece matching them hasn't been found so far.
Oktavia von Seckendorff
When Oktavia von Seckendorff is born from Sayaka's despair, multiple notes appear floating around unobstructed. Because the notes are visible for an adequate period of time and there' nothing blocking them, it didn't take long before the first sheets appeared on 4chan's /a/ board. After a few more or less unsuccessful attempts to transcript the notes, a video appeared on Nico Nico Douga pointing out the similarities between the sheet music and the background music that was playing during the episode's two battle scenes.
The problems encountered during the transcription process were mostly related to the video quality and capabilities of human eye. The whole sheet music is displayed in various places throughout the first battle scene and again in the very end of the episode, so making the correct transcription was just a matter of finding the best shots of the notes. Unlike in the spell circle, this sheet had clear bar lines which made it possible to determine a time signature, and the notation was overall more consistent which made it easier to work on. The first transcription that appeared on /a/ was based on the assumption that the scores were flipped vertically, which they weren't. In addition some of the quarter notes in it lacked dots which caused some bars to have less beats than the others. It also began from the wrong place, the first bar was determined after a double line was discovered from the sheet music, and later proven correct after the connection to the bgm was discovered. The second transcription had established the 6/4 time signature, and had reconstructed the notes as they appeared in the episode rather than flipping them over vertically. However, due to some of the natural accidents that appear in several bars, the anon had determined the key signature to be Ab minor. Closer inspection of a picture compiled from screenshots revealed that the natural accidentals were actually a result of sharp notes appearing in previous bars. These accidents are more clearly visible on the screen after the endcard.