“…As described above, DataGuides use graphs as the general form to represent the common structures of XML collections. DataGuides, however, are not as expressive as Data Type Definitions (DTDs) (Bex et al, 2005;Bex et al, 2006;Chidlovskii, 2001;Garofalakis et al, 2003;Min, Ahn, & Chung, 2003;Sankey & Wong, 2001) or XML Schema (Bex et al, 2007;Bex et al, 2008;Clark;Hegewald et al, 2006), the two most widely used formats to represent the structure of XML documents.…”