Editing Key signature (section)

=== Variations ===
{{unreferenced|section|date=May 2025}}
In the past, when a key signature changes from sharps to flats or vice versa, the old key signature was cancelled with a matching set of naturals before the new key signature was shown. Newer music and newer editions of older music dispense with the naturals and simply insert the new signature, unless the new key signature has no sharps or flats (C major, A minor, or an open key signature), in which case the cancelling natural signs are necessary.

Similarly, when a flat key changes to fewer flats, or a sharp key changes to fewer sharps, the convention was to use naturals to cancel the flats or sharps that are being subtracted before the new signature is written. Modern usage often simply shows the new signature without these naturals. As in the previous cases, the use of natural signs is required if the new key signature has no sharps or flats.

When a flat key changes to more flats or a sharp key changes to more sharps, the new signature is simply written in without using naturals to cancel the old signature. This convention applies in both traditional and newer styles.

At one time it was usual to precede the new signature with a [[barline|double barline]] even if it was not otherwise required, but it has become increasingly common to simply use a single barline. The courtesy signature that appears at the end of a line immediately before a change is usually preceded by an additional barline and the line at the very end of the staff is omitted.

If both naturals and a new key signature appear at a key signature change, there are also modern variations about where a barline will be placed. In some scores by Debussy the barline is placed after the naturals but before the new key signature. Hitherto, it would have been usual to place all the symbols after the barline.

The A{{music|sharp}} which is the fifth sharp in the sharp signatures may occasionally be notated on the top line of the bass staff, whereas it is more usually found in the lowest space on that staff. An example of this can be seen in the full score of [[Ottorino Respighi]]'s ''[[Pines of Rome]]'', in the third section, "Pines of the Janiculum" (which is in [[B major]]), in the bass-clef instrumental parts.

In the case of seven-flat key signatures, the final F{{music|flat}} may occasionally be seen on the second-top line of the bass staff, whereas it would more usually appear on the space below the staff. An example of this can be seen in [[Isaac Albéniz]]'s ''[[Iberia (Albéniz)|Iberia]]'': first movement, "Evocación", which is in [[A-flat minor|A{{music|flat}}]] minor.