Original sentence: Since the DTD of the extended format must be available to a decoder to allow reading of the data, it's not extensible in the same way that XML is; unlike XML, a DTD of a previous version, or no DTD, is not useful
Edited sentence: Unfortunately it fails the "extensible" part of its name due to the fact that the DTD of the extended format must be available to a decoder to allow reading of the data.Unlike XML, a DTD of a previous version, or no DTD, is not useful