[xml] validation automatically turned on?

[Stefano Debenedetti <ste webaccess mozquito com>]

Hi, I am experiencing a strange behavior using libxml2.5.1 python bindings on a debian woody: I have an 
application that parses many xml files and one of them is an xhtml file referencing the dtd on the w3c site. 
It seems that when parsing that file validation is turned on even if i just use a libxml2.parseFile call...
I also tried to create a parser context and call validate(0) on it but validation happens anyway...
I tried to do the same thing using the interactive python shell but I cannot replicate the behavior: the same 
code does not do validation, as expected.
Are there any circumstances under which validation is automatically turned on?

Thanks, ciao
ste