xml-dev - SAX2 and Transformation ?

[Sunny <sandeepsethi@email.msn.com>]

As I understand it  - SAX lets you stream the xml data, providing events
that can be trapped as and when needed.
So, biggest advantage - it doesn't  have to maintain an in-memory tree of
the document.
Two questions here -
1) Without loading the document, how does a sax-based parser know that the
document is valid  and well-formed ? Is that something that I sacrifice when
I use a sax - parser ?

2a) Now, the document hasn;t been loaded yet , so how do I apply
transformation or xsl-fo to the xml-document ? Is that something that 'they'
are still trying to figure out - or is there some documentation somewhere

2b) Does Xalan do this ?


( thanks Simon for the earlier reply)