# RELAX NG Schema for OpenMath 2


default namespace om = "http://www.openmath.org/OpenMath"

start = OMOBJ

# OpenMath object constructor
OMOBJ = element OMOBJ { compound.attributes,
                        attribute version { xsd:string }?,
                        omel }


# Elements which can appear inside an OpenMath object
omel = 
  OMS | OMV | OMI | OMB | OMSTR | OMF | OMA | OMBIND | OME | OMATTR |OMR

# things which can be variables
omvar = OMV | attvar

attvar = element OMATTR { common.attributes,(OMATP , (OMV | attvar))}


cdbase = attribute cdbase { xsd:anyURI}?

# attributes common to all elements
common.attributes = (attribute id { xsd:ID })?

# attributes common to all elements that construct compount OM objects.
compound.attributes = common.attributes,cdbase

# symbol
OMS = element OMS { common.attributes,
                    attribute name { xsd:NCName},
                    attribute cd { xsd:NCName},
                    cdbase }

# variable
OMV = element OMV { common.attributes,
                    attribute name { xsd:NCName} }

# integer
OMI = element OMI { common.attributes,
                    xsd:string {pattern = "\s*(-\s?)?[0-9]+(\s[0-9]+)*\s*"}}
# byte array
OMB = element OMB { common.attributes, xsd:base64Binary }

# string
OMSTR = element OMSTR { common.attributes, text }

# IEEE floating point number
OMF = element OMF { common.attributes,
                    ( attribute dec { xsd:double } |
                      attribute hex { xsd:string {pattern = "[0-9A-F]+"}}) }

# apply constructor
OMA = element OMA { compound.attributes, omel+ }

# binding constructor 
OMBIND = element OMBIND { compound.attributes, omel, OMBVAR, omel }

# variables used in binding constructor
OMBVAR = element OMBVAR { common.attributes, omvar+ }

# error constructor
OME = element OME { common.attributes, OMS, (omel|OMFOREIGN)* }

# attribution constructor and attribute pair constructor
OMATTR = element OMATTR { compound.attributes, OMATP, omel }

OMATP = element OMATP { compound.attributes, (OMS, (omel | OMFOREIGN) )+ }

# foreign constructor
OMFOREIGN =  element OMFOREIGN {
    compound.attributes, attribute encoding {xsd:string}?,
   (omel|notom)* }

# Any elements not in the om namespace
# (valid om is allowed as a descendant)
notom =
  (element * - om:* {attribute * { text }*,(omel|notom)*}
   | text)

# reference constructor
OMR = element OMR { common.attributes,
                    attribute href { xsd:anyURI }
                  }