[ZPT] define-slot nested inside fill-slot

[Tim Lynch]

In Plone's main_template there are the following lines:


   <metal:block fill-slot="css_slot">
      <metal:block define-slot="css_slot" />
   </metal:block>



Can someone explain the purpose of the define-slot statement
inside the fill-slot? Is it to serve as some sort of default
definition?

The "real" define-slot for css_slot is in header.pt as
expected, so what's the purpose of this one?  As I understand
ZPT, even if css_slot weren't defined in header.pt, no error
would be thrown even if the above trick define-slot weren't
used.


--
tim lynch
tlynch at nal.usda.gov