[xml] noob xpath question

[Stefan Jeglinski <jeglin 4pi com>]

There's likely a better list for this, but I've been spending 
most/all of my time at xmlsoft.org. I'm teaching myself xml, and I 
must be braindead - I just can't get past this one.

I've got xmllib2 compiled, and can compile and run a variety of the 
test code examples. I'm trying to get my head around xpath. Here is 
my toy xml file:

<?xml version="1.0" standalone="yes"?>
<!DOCTYPE myroot [
<!ELEMENT myroot (myelement+)>
<!ELEMENT myelement (x,y)>
<!ATTLIST myelement type (a | b) #REQUIRED>
<!ELEMENT x (#PCDATA)>
<!ELEMENT y (#PCDATA)>
]>
<myroot>
        <myelement type="a">
                <x>1a</x>
                <y>2a</y>
        </myelement>
        <myelement type="b">
                <x>1b</x>
                <y>2b</y>
        </myelement>
</myroot>


Using the xpath1.c sample code, I can successfully find element 
nodes, but I can't "subselect" based on type. for example, this xpath:

        /myroot/myelement/@type

returns 2 type nodes (as expected?), but no matter what syntax I've 
tried (I've googled, looked in books), I cannot select type a or b by 
itself, for example with umpteen variants of something along these 
lines:

        /myroot/myelement/@type[.='a']

I suspect I'm barking up the wrong tree (not to pun). Am I misusing 
xpath, probably on several levels? Have I missed a really dumb step 
in building the xml file to begin with? Other? Ultimately I want to 
be able to specify one element alone in the xml document using xpath 
- it's not so much that any final implementation will work like 
this... I just want to understand it.


Stefan Jeglinski