<fo:leader> 对象的作用如下：
如果前导字符长度太长，与整个区域明显不适应，那么它将会另起一行。
只用在 leader-pattern 属性设置为 "use-content" 的情况下，<fo:leader> 对象的子类才不会被忽略；如果 <fo:leader> 不包含子类，并且 leader-pattern 属性设置为 "use-content"，那么前导字符会被填充为空白。
如果前导字符需要在一行中填充所有的空格，那么前导字符的最大长度至少与列的宽度相同。
<fo:leader>
<!--
Contents:(#PCDATA|bidi-override|character|
external-graphic|instream-foreign-object|
inline|page-number|page-number-citation|
basic-link|multi-toggle)*
-->
</fo:leader>
| 属性 [A-K] | 属性 [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 |