[AccessD] ADO Save recordset format adPersistADTG

Hi all

With ADO you can save a recordset to a file, normally an XML file, but another format, Microsoft Advanced Data TableGram, exists:

  rst.Save "d:\temp\records.dat", adPersistADTG

Where or why could this binary format be used? 
It creates file sizes about 1/3 of the XML file created if adPersistXML had been used.
Is it just a proprietary format for storing and retrieval of data to/from a single external file?

/gustav