[Zope] Why does Zope insert a <BASE > tag?

Hi, I was wondering why Zope inserts a <BASE HREF="..."> tag into each page? Is there any way you can change what it inserts? The reason I ask it's currently putting in the wrong thing. Here's the situation: We have several sites on one Zope installation, set up as follows: zope.nipltd.com/project1 zope.nipltd.com/project2 zope.nipltd.com/project3 ...etc... These are also served up through Apache as follows: www.project1.com www.project2.com ...etc... Now in this second case, the base tag inserted is something like: <base href="http://www.project1.com/project1/"> which is wrong and is causing things to break... How can I go about correcting/removing this base tag? cheers, Chris