[Lazarus] Generic XML question

[Marc Weustink]

Hi,
This is not a specific lazarus question, but since here might be xml 
users, I'll ask it here.
At my work our software interfaces with a lot of different systems, some 
of them communicate through a binary protocol and some of them use xml 
to encode data. YEars ago we coded our own xml parser (creates an object 
tree of elements found) / generator (generates xml form such tree)
Anyway each time I have to communicate with xml there are some "issues"
One system for instance doesn't like spaces before the first element or 
a linefeed after the closing element. Another system ignores the xml 
message when it encounters an not yet known element (its hard to 
implement forward/backward compatibility this way). Yesterday I was 
working on a new system and that one complained about unparseble xml 
when I put some whitespace (space, linefeed) between the first opening 
tag end the second opening tag.

Now I wonder, is xml supposed to be so strict or are this implementation 
"issues"

Marc