Does xmls nodes sequence matter?

Question

are

<parent>
    <first_child>1111111</first_child>
    <second_child>2222222</second_child>
</parent>  

and

<parent>
    <second_child>2222222</second_child>
    <first_child>1111111</first_child>
</parent>

should be considered as xmls with the same structure or not?

Answer 1

It entirely depends on what's going to interpret the XML.

Imagine it's actually HTML, and these are paragraph tags... obviously the order matters. In other cases, it may not.

Answer 2

It depends on the schema that is used to validate it.

Answer 3

It basically depends on how you define your schema, e.g. with XSD you can use all if order does not matter or sequence if it does. See the w3schools page for details.