reminds me of a description of MSFT's first XML-based office file formats (not sure if its true or was a joke) but it went something like
<xml> <office-proprietary-binary-blob> wky4b5tlwybkjbb2... </office-proprietary-binary-blob> </xml>
<xml> <office-proprietary-binary-blob> wky4b5tlwybkjbb2... </office-proprietary-binary-blob> </xml>
And it seems after 2007 they switched to an ECMA standard.