Colour of Word XML elements

[Rob Stewart]

Is anyone able to tell me why the image used to mark XML
elements in Word changes from a grey fill to a purple fill?
The grey one has the name of the element in both the
opening and closing tags, while the purple has a shortened
closing tag containing no text.

It seems to be that when an element is first inserted into
a Word doc., it is in the 'grey mode', but as soon as you
type text immediately after the element, it goes
to 'purple mode' which doesn't allow carriage returns
within the element.

I'm sure there's a reason for this...?

Rob