well-formed YDML definition in Relax NG Compact Syntax

ydml.rnc

start = element ydml { Block* }
Block = Paragraph* & Center* & Left* & Right* & Quote* & Hasen*
Paragraph = Inline +
Inline = Large|Small|Bold|Image|Ruby|text
Center = element center { Inline+ }
Left = element left { Inline+ }
Right = element right { Inline+ }
Quote = element quote { Inline+ }
Hasen = element hasen { empty }

Large = element large { Inline+ }
Small = element small { Inline+ }
Bold = element bold { Inline+ }
Ruby = element ruby { text }

Image =
  element image {
    attribute src { text },
    attribute size { text }?
  }