<grammar xmlns="http://relaxng.org/ns/structure/1.0"> <start> <element name="p"> <ref name="inline"/> </element> </start> <define name="inline"> <zeroOrMore> <choice> <text/> <element name="bold"> <ref name="inline"/> </element> <element name="italic"> <ref name="inline"/> </element> <element name="span"> <optional> <attribute name="style"/> </optional> <ref name="inline"/> </element> </choice> </zeroOrMore> </define> </grammar>