How is the loading - XML ​​DOM object into memory, from disk?

Question

C++ / C#

Happy New Year everyone !
A question regarding loading XML Dom Objects, by calling which functions of the Win Kernel, does the XML object directly load from disk to memory?
From the example, you can only see an indication of the load method, with the transfer of the name and value bool to the stack.
pXMLDom->load(varFileName, &varStatus));
But what is load ? Is there a call to ntCreateFileA&W, or is it loading in some other way?