Editing Numbered musical notation (section)

===Accidentals and key signature===
The notation uses a [[Solfège#Variations|movable Do (1)]] system. The [[key signature]] defines the [[pitch (music)|pitch]] of "1". So <code>1=C</code> means "C major". Minor keys are based on the [[natural minor]] or the [[Aeolian mode]], and the key signature defines the pitch of "6" of the minor key's [[relative major]]. <code>6=A</code> can be used to refer to A minor, the tonic of which is written as 6. Naturally, the [[Dorian mode]] of D can in principle be marked as <code>2=D</code> and based on 2. In common practice, however, either are normally denoted as <code>1=C</code>.

The same [[Accidental (music)|accidental]]s in the [[musical notation|standard notation]] are used, and as in common practice, an accidental is placed before the notes "1 2 3 4 5 6 7" to raise or lower the pitch and placed after the note names "C D E F G A B", which are used for key signature and [[chord (music)|chord]] markings in the numbered system. But these accidentals are relative to the diatonic scale (1 2 3...) rather than the note names (C D E...). For example, even though the [[leading note]] for the harmonic C minor scale is B natural, it is written as "{{music|sharp}}5".

In the Indonesian version of numbered musical notation known as "not angka", accidentals are notated using right slanted line (like /) to raise the tone a half step and left slanted line (like \) to lower the tone a half step, for example: 1/ read as C{{music|sharp}}, 2/ read as D{{music|sharp}}, 4/ read as F{{music|sharp}}, 5/ read as G{{music|sharp}}, 6/ read as A{{music|sharp}}, 2\ read as D{{music|flat}}, 3\ read as E{{music|flat}}, 5\ read as G{{music|flat}}, 6\ read as A{{music|flat}} and 7\ read as B{{music|flat}}.  In printed not angka, these lines are overprinted on the figures.<ref>[https://github.com/ssb22/jianpu-ly/commit/4e298df57f2d50f0ad40a1b956358462e7d872a5#diff-15b0e0397d48477041da317f9233cef54fe7478371a2f84e107bd403b7221267R312 jianpu-ly not-angka commit line 312]</ref>

Key signature changes are marked above the line of music. They may be accompanied by symbols that represent the note's degrees at previous and present key signatures.