A convenient compact syntax

Compact, familiar While RELAX NG has an XML syntax, it also supports a compact syntax that's generally easier to edit. RELAX NG Compact Syntax uses some abbreviations and conventions from DTDs, minus the angle brackets, and is generally readable to anyone who's worked with DTDs before.
Declarations look like declarations.
name=element name{element givenName, element familyName}
DTD modifiers work as expected. ? for zero or one, * for zero or more, comma for sequence, | for or, plus (like SGML) & for interleave.
book=element book {title, author+, license?, chapter+, appendix*}
Can use WXS Datatypes RELAX NG supports WXS datatypes (technically, libraries are pluggable), so using datatypes in declarations is easy:
number=element number {xsd:integer}
A start pattern Neither DTDs nor WXS provide a means of identifying which element should be the root element of a document - even as a suggestion. RELAX NG provides a convenient start pattern for this as well.