### 4.1.4 Flexible vertical spacing \paper variables

In most cases, it is preferable for the vertical distances between certain items (such as margins, titles, systems, and separate scores) to be flexible, so that they stretch and compress nicely according to each situation. A number of \paper variables (listed below) are available to fine-tune the stretching behavior of these dimensions.

Note that the \paper variables discussed in this section do not control the spacing of staves within individual systems. Within-system spacing is controlled by grob properties, with settings typically entered inside a \score or \layout block, and not inside a \paper block. See Flexible vertical spacing within systems.

#### Structure of flexible vertical spacing alists

Each of the flexible vertical spacing \paper variables is an alist (association list) containing four keys:

• basic-distance – the vertical distance, measured in staff-spaces, between the reference points of the two items, when no collisions would result, and no stretching or compressing is in effect. The reference point of a (title or top-level) markup is its highest point, and the reference point of a system is the vertical center of the nearest StaffSymbol – even if a non-staff line (such as a Lyrics context) is in the way. Values for basic-distance that are less than either padding or minimum-distance are not meaningful, since the resulting distance will never be less than either padding or minimum-distance.
• minimum-distance – the smallest allowable vertical distance, measured in staff-spaces, between the reference points of the two items, when compressing is in effect. Values for minimum-distance that are less than padding are not meaningful, since the resulting distance will never be less than padding.
• padding – the minimum required amount of unobstructed vertical whitespace between the bounding boxes (or skylines) of the two items, measured in staff-spaces.
• stretchability – a unitless measure of the dimension’s relative propensity to stretch. If zero, the distance will not stretch (unless collisions would result). When positive, the significance of a particular dimension’s stretchability value lies only in its relation to the stretchability values of the other dimensions. For example, if one dimension has twice the stretchability of another, it will stretch twice as easily. Values should be non-negative and finite. The value +inf.0 triggers a programming_error and is ignored, but 1.0e7 can be used for an almost infinitely stretchable spring. If unset, the default value is set to basic-distance. Note that the dimension’s propensity to compress cannot be directly set by the user and is equal to (basic-distance - minimum-distance).

If a page has a ragged bottom, the resulting distance is the largest of:

• basic-distance,
• minimum-distance, and
• padding plus the smallest distance necessary to eliminate collisions.

For multi-page scores with a ragged bottom on the last page, the last page uses the same spacing as the preceding page, provided there is enough space for that.

Specific methods for modifying alists are discussed in Modifying alists. The following example demonstrates the two ways these alists can be modified. The first declaration updates one key-value individually, and the second completely redefines the variable:

\paper {
system-system-spacing.basic-distance = #8
score-system-spacing =
#'((basic-distance . 12)
(minimum-distance . 6)
(stretchability . 12))
}

#### List of flexible vertical spacing \paper variables

The names of these variables follow the format upper-lower-spacing, where upper and lower are the items to be spaced. Each distance is measured between the reference points of the two items (see the description of the alist structure above). Note that in these variable names, the term ‘markup’ refers to both title markups (bookTitleMarkup or scoreTitleMarkup) and top-level markups (see File structure). All distances are measured in staff-spaces.

Default settings are defined in ‘ly/paper-defaults-init.ly’.

markup-system-spacing

the distance between a (title or top-level) markup and the system that follows it.

score-markup-spacing

the distance between the last system of a score and the (title or top-level) markup that follows it.

score-system-spacing

the distance between the last system of a score and the first system of the score that follows it, when no (title or top-level) markup exists between them.

system-system-spacing

the distance between two systems in the same score.

markup-markup-spacing

the distance between two (title or top-level) markups.

last-bottom-spacing

the distance from the last system or top-level markup on a page to the bottom of the printable area (i.e., the top of the bottom margin).

top-system-spacing

the distance from the top of the printable area (i.e., the bottom of the top margin) to the first system on a page, when there is no (title or top-level) markup between the two.

top-markup-spacing

the distance from the top of the printable area (i.e., the bottom of the top margin) to the first (title or top-level) markup on a page, when there is no system between the two.