File Paths to load files with WWW for WebGL

Is there a restriction on where files can be loaded from when using the WWW object?
Should I expect the same behavior when I deploy to the server?

I am testing using the Firefox browser console by double clicking on the index.html.

"C:\FileLoaderTest\build\html5" --> This is where my WebGL build is deployed.

I placed an xml file in three different locations and used the following urls to access the files:

...inside the same directory as the index.html

"file:///C:/FileLoaderTest/build/html5/TestFile.xml" --> Loads as expected.

...in the root directory

"file:///C:/TestFile.xml" --> Does not load.

...in a sub directory

"file:///C:/FileLoaderTest/build/html5/Config/TestFile.xml" --> Does not load.