35.1 Overview of modifying properties

Within each context, there are two different kinds of properties: context properties and grob properties. Context properties apply to a context as a whole, whereas grob properties are used for initializing grobs engraved from within a context.

Context properties control the translation from music to notation. For example, localAlterations is used to determine whether to print accidentals; or currentBarNumber for determining which bar number to print. They can also change value over time while interpreting a piece of music; currentBarNumber is an obvious example of this.

The \set command (and its counterpart \unset) is used to alter values for context properties, whereas the \override command (and its counterpart \revert) is used to change values for grob properties.