From http://www.w3schools.com (Copyright Refsnes Data)

XSL-FO leader Object

Definition and Usage

The <fo:leader> object can be used used to:

generate "." to separate titles from page numbers in table of contents
create input fields in forms
create horizontal rules

If the leader's length is too long to fit in the area, the leader will begin a new line.

The children of the <fo:leader> object are ignored unless the leader-pattern property is "use-content". If the <fo:leader> has no children and the leader-pattern property is "use-content", the leader is filled with blank space.

If the leader should fill all space on a line, the max length of the leader should be at least as large as the width of the column.

Syntax

<fo:leader>
  <!--
	Contents:(#PCDATA|bidi-override|character|
	external-graphic|instream-foreign-object|
	inline|page-number|page-number-citation|
	basic-link|multi-toggle)*
  -->
</fo:leader>

Properties

Property [A-K]	Property [L-Z]
azimuth	leader-alignment
alignment-adjust	leader-length
alignment-baseline	leader-pattern
background-attachment	leader-pattern-width
background-color	left
background-image	letter-spacing
background-repeat	line-height
background-position-horizontal	margin-bottom
background-position-vertical	margin-left
baseline-shift	margin-right
border-after-color	margin-top
border-after-style	padding-after
border-after-width	padding-before
border-before-color	padding-bottom
border-before-style	padding-end
border-before-width	padding-left
border-bottom-color	padding-right
border-bottom-style	padding-start
border-bottom-width	padding-top
border-end-color	pause-after
border-end-style	pause-before
border-end-width	pitch
border-left-color	pitch-range
border-left-style	play-during
border-left-width	relative-position
border-right-color	richness
border-right-style	right
border-right-width	role
border-start-color	rule-style
border-start-style	rule-thickness
border-start-width	source-document
border-top-color	space-end
border-top-style	space-start
border-top-width	speak
bottom	speak-header
color	speak-numeral
cue-after	speak-punctuation
cue-before	speech-rate
dominant-baseline	stress
elevation	text-altitude
font-family	text-depth
font-selection-strategy	text-shadow
font-size	top
font-size-adjust	visibility
font-stretch	voice-family
font-style	volume
font-variant	word-spacing
font-weight
id
keep-with-next
keep-with-previous