XF 1.5 Where to edit a publiclink built?

[Stockwalker]

I understand the logic in Link.php builds links which get called from other files. However, where is the logic for the endpoint that then gets 'built' by it?
I have this POST request:
<xen:form action="{xen:adminlink 'post-macros/admin/save'}" method="post" class="AutoValidator" data-redirect="on">