[Zope] entity reference form of the var tag

[Tom Deprez]

Can somebody give me more information on this 'entity reference form'?
Where can I find more information about it?

and why is :

<a href="&dtml-URL1;/spam>

the same as :

<a href="<dtml-var spam>">

referring jim's how-to 'generate URLs for Objects'

Tom.