I would like to know if there are any xml coding standards.

```
<?xml version="1.0"?>
<overlay id="tutorboy-toolbar-Overlay" xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
    <toolbox id="navigator-toolbox">
        <toolbar id="tutorboy-toolbar-Toolbar" 
                  toolbarname="TutorBoy Toolbar" 
                  accesskey="T" 
                  class="chromeclass-toolbar" 
                  context="toolbar-context-menu" 
                  hidden="false" 
                  persist="hidden">
              <toolbarbutton label="TutorBoy" 
                                id="tutorboy-toolbar-button-home" 
                                accesskey="d" 
                                image="chrome://tutorboy-toolbar/skin/logo.png" 
                                oncommand="loadURL('http://tutorboy.com');" 
                                tooltiptext="Click here to go to the Tutorboy.com homepage." /> 

```

is this way of arrangement allowed?