namespace rng = "http://relaxng.org/ns/structure/1.0"
namespace xsd  = "http://www/w3/org/2001/XMLSchema-datatypes"
namespace xml  = "http://www.w3.org/XML/1998/namespace"
namespace cal  = "http://example.org/ns/cal"
default namespace = "http://example.org/ns/dhcp"

start = element-dhcp

element-dhcp = element dhcp {
   global-timer-elements,
   element-subnet*,
   element-shared-network*
}

global-timer-elements = (
   element default-lease-time { xsd:unsignedInt }?,   
   element max-lease-time { xsd:unsignedInt }?      
)

element-shared-network = element shared-network {
   attribute name { token },
   element-subnet+
}

element-subnet = element subnet {
   element-network,
   element-prefix-length,
   element-range?,
   element-dhcp-options?,
   element max-lease-time { xsd:unsignedInt }?,
   element leases {
     element-lease*
   }?,
   element-interface-filter?
}

element-network = element network {
   ipv4-address-content
}
element-prefix-length = element prefix-length { 
   xsd:short { minInclusive = "0" maxInclusive = "32" } 
}

element-range = element range {
   element dynamic-bootp { empty }?,
   element low  { ipv4-address-content },
   element high { ipv4-address-content }
}

element-dhcp-options = element dhcp-options {
   element-router-list-option?,
   element-domain-list-option?,
   element-custom-option*,
   element cal:timezone { token }?
}

element-lease = element lease {
   attribute ip-address { ipv4-address-content },
   element starts  { xsd:dateTime },
   element ends    { xsd:dateTime },
   element mac-address { mac-address-content }
}

element-router-list-option = element router-list {
   element router { ipv4-address-content }+
}
element-domain-list-option = element domain-list {
   element domain { token }+
}
element-custom-option = element custom {
   attribute option { xsd:unsignedByte },
   ( 
       element ip-address { ipv4-address-content } 
     | element string { string } 
   )
}

element-interface-filter = element interface-filter {
  element interface { token }+
}

ipv4-address-content = xsd:token { pattern = 
  "((25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])\.){3}(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|[1-9][0-9]|[0-9])" 
  }
mac-address-content  = xsd:token { 
  pattern = "(([0-9a-fA-F]{2}):?){5}[0-9a-fA-F]{2}" 
}