XML root node with slash... unexplained?

Why would you have a rootnode in an XML document that looks like this:

<return/>

Why is that slash there? I 开发者_运维知识库have never seen an XML document like this, however in an application I am debugging, a root node looking like this one is created, and appending any child nodes seems to be failing.

Removing the slash crashes the program.

It uses MSXML DOM in C++ under windows.

<foo/> is equivalent to <foo></foo>. This is known as an empty element. Without the ending /, the open tag will not have a corresponding closing tag, and thus an error.

That is the root node of the xml document and it has no child elements. That's why it has no ending tag.