Cross references

https://github.com/modxcms/evolution/blob/v1.2/manager/includes/document.parser.class.inc.php#L972-L1045

[*pagetitle@3*]
[*pagetitle@parent*]
[*pagetitle@ultimateParent*] or [*var@uParent*]
[*pagetitle@ultimateParent(3)*]
[*pagetitle@prev*]
[*pagetitle@next*]
[*pagetitle@alias(aliasname)*]
[*pagetitle@alias(parentAlias/subAlias)*]
[*pagetitle@site_start*]

<@IF:[*id@next*]><a href="[~[*id@next*]~]">[*pagetitle@next:strip_tags*]</a><@ENDIF>

(Do not distinguish between uppercase and lowercase letters)

If you understand the meaning, please help to write a more detailed document.