### 2.1.2 Pitches and key signatures

Note: New users often misunderstand how LilyPond uses the key signature – please read the warning at the end of this section.

#### Pitch alterations

Music Glossary: sharp, flat, double sharp, double flat, accidental.

Note names in LilyPond identify pitches. For example, ‘c’ always means C-natural, regardless of the key signature.

In many languages, a note name consists of a base name referring to the diatonic steps of the C major/a minor scale (for example, ‘d’) and a suffix, which indicates alteration of this base pitch. The default input language for note names is ‘nederlands’ (Dutch). A sharp pitch is made by adding ‘is’ to the name, and a flat pitch by adding ‘es’. As you might expect, a double sharp or double flat is made by adding ‘isis’ or ‘eses’. This syntax is derived from note naming conventions in Nordic and Germanic languages, like German and Dutch. To use other naming schemes for note names, see Note names in other languages.

\relative { cis''4 ees fisis, aeses }


#### Key signatures

Music Glossary: key signature, major, minor.

The key signature is set with the command \key followed by a pitch and \major or \minor.

\relative {
\key d \major
d'4 fis a c |
\bar "||" \key c \minor
c,4 ees g b |
}


#### Warning: key signatures and pitches

Music Glossary: accidental, key signature, pitch, flat, natural, sharp, transposition, Pitch names.

LilyPond makes a distinction between musical content and its printed representation. Input such as ‘d4 e fis2’ defines the pitches and durations of notes, which is musical content. The key signature is part of the printed representation. The key signature also sets rules for the printed representations of notes. LilyPond compares each input pitch to the key signature to determine whether to print an accidental.

The command \key sets the key signature, which affects the printed representation, but does not change the pitch assigned to a note such as ‘c’ in the input.

Consider this example.

\relative {
\key d \major
cis''4 d e fis
}


No note has a printed accidental, but you must still add ‘is’ and type ‘cis’ and ‘fis’ in the input file.

The code ‘b’ does not mean “print a thick black dot just on the middle line of the staff”. Rather, it means “there is a note with pitch B-natural”. In the key of A-flat major, it does get an accidental:

\relative {
\key aes \major
aes'4 c b c
}


To say it differently: Whenever you enter a pitch that is a black key on the piano, you must add ‘is’ or ‘es’ to the note name.

Adding all alterations explicitly might require a little more effort when typing, but the advantage is that transposing is easier, and accidentals can be printed according to different conventions. For some examples of how accidentals can be printed according to different rules, see Automatic accidentals.