1<grammar xmlns="http://relaxng.org/ns/structure/1.0"> 2 3<define name="cell.content"> 4 <notAllowed/> 5</define> 6 7<start> 8 <element name="table"> 9 <oneOrMore> 10 <element name="tr"> 11 <oneOrMore> 12 <element name="td"> 13 <ref name="cell.content"/> 14 </element> 15 </oneOrMore> 16 </element> 17 </oneOrMore> 18 </element> 19</start> 20 21</grammar> 22