38.12.1 Specified Spaces

To display a space of specified width and/or height, use a display specification of the form (space . props), where props is a property list (a list of alternating properties and values). You can put this property on one or more consecutive characters; a space of the specified height and width is displayed in place of all of those characters. These are the properties you can use to specify the weight of the space:

:width width

Specifies that the space width should be width times the normal character width. width can be an integer or floating point number.

:relative-width factor

Specifies that the width of the stretch should be computed from the first character in the group of consecutive characters that have the same display property. The space width is the width of that character, multiplied by factor.

:align-to hpos

Specifies that the space should be wide enough to reach hpos. The value hpos is measured in units of the normal character width. It may be an interer or a floating point number.

Exactly one of the above properties should be used. You can also specify the height of the space, with other properties:

:height height

Specifies the height of the space, as height, measured in terms of the normal line height.

:relative-height factor

Specifies the height of the space, multiplying the ordinary height of the text having this display specification by factor.

:ascent ascent

Specifies that ascent percent of the height of the space should be considered as the ascent of the space--that is, the part above the baseline. The value of ascent must be a non-negative number no greater than 100.

You should not use both :height and :relative-height together.