### 1.1.100 UnrelativableMusic

Music that cannot be converted from relative to absolute notation. For example, transposed music.

Properties:

> `iterator-ctor` (procedure):

>   `ly:music-wrapper-iterator::constructor`

>   Function to construct a `music-event-iterator` object for this music.

> `length-callback` (procedure):

>   `ly:music-wrapper::length-callback`

>   How to compute the duration of this music. This property can only be defined as initializer in ‘`scm/define-music-types.scm`’.

> `name` (symbol):

>   `'UnrelativableMusic`

>   Name of this music object.

> `to-relative-callback` (procedure):

>   `ly:relative-octave-music::no-relative-callback`

>   How to transform a piece of music to relative pitches.

> `types` (list):

>   `'(music-wrapper-music general-music unrelativable-music)`

>   The types of this music object; determines by what engraver this music expression is processed.

#### Internals Reference v2.18.2 (稳定分支).