What is an XSLT tree ?

Hi,




I found on a quiz the following question:

“Which of the following accurately describe the types of nodes that can 
be presented in an XSLT tree ?”

Answer: Root, element, text, attribute.

Motivation:

An XSL processor recognizes 7 kinds of nodes: Root, elements, text, 
attributes, namespaces, processing instructions and comments. XSLT only 
deals with the above mentioned four nodes.

How can this be true ? For example there is a function called 
processing-instruction() that will select PIs. I can detect a PI and 
output something when a PI is found. The same is true for comments.

I may not understand the question because I lack the required 
theoretical knowledge. What is an XSLT tree ?



Regards,
Razvan