<grammar xmlns="http://relaxng.org/ns/structure/1.0"> <define name="cd.token.unary.class" combine="choice"> <ref name="momentabout.token"/> </define> <define name="cd.token.nary.class" combine="choice"> <choice> <ref name="mean.token"/> <ref name="sdev.token"/> <ref name="variance.token"/> <ref name="median.token"/> <ref name="mode.token"/> <ref name="moment.token"/> </choice> </define> <define name="mean.content"> <ref name="Token.type"/> </define> <define name="mean.token"> <element name="mean"> <ref name="mean.content"/> </element> </define> <define name="sdev.content"> <ref name="Token.type"/> </define> <define name="sdev.token"> <element name="sdev"> <ref name="sdev.content"/> </element> </define> <define name="variance.content"> <ref name="Token.type"/> </define> <define name="variance.token"> <element name="variance"> <ref name="variance.content"/> </element> </define> <define name="median.content"> <ref name="Token.type"/> </define> <define name="median.token"> <element name="median"> <ref name="median.content"/> </element> </define> <define name="mode.content"> <ref name="Token.type"/> </define> <define name="mode.token"> <element name="mode"> <ref name="mode.content"/> </element> </define> <define name="moment.content"> <ref name="Token.type"/> </define> <define name="moment.token"> <element name="moment"> <ref name="moment.content"/> </element> </define> <define name="momentabout.content"> <ref name="Token.type"/> </define> <define name="momentabout.token"> <element name="momentabout"> <ref name="momentabout.content"/> </element> </define> </grammar>