old_contents: from sfa.util.enumeration import Enum
  
  # recognized top level rspec elements
  RSpecElements = Enum(
      BWLIMIT='BWLIMIT',
      EXECUTE='EXECUTE',
      NETWORK='NETWORK', 
      COMPONENT_MANAGER='COMPONENT_MANAGER',
      INSTALL='INSTALL', 
      INTERFACE='INTERFACE', 
      INTERFACE_REF='INTERFACE_REF',
      LOCATION='LOCATION', 
      LOGIN='LOGIN', 
      LINK='LINK', 
      LINK_TYPE='LINK_TYPE', 
      NODE='NODE', 
      PROPERTY='PROPERTY',
      SERVICES='SERVICES',
      SLIVER='SLIVER', 
      SLIVER_TYPE='SLIVER_TYPE', 
  )
  
  class RSpecElement:
      def __init__(self, element_type, path):
          if not element_type in RSpecElements:
              raise InvalidRSpecElement(element_type)
          self.type = element_type
          self.path = path
  
new_contents: from sfa.util.enumeration import Enum
  
  # recognized top level rspec elements
  RSpecElements = Enum(
      AVAILABLE='AVAILABLE',
      BWLIMIT='BWLIMIT',
      EXECUTE='EXECUTE',
      NETWORK='NETWORK', 
      COMPONENT_MANAGER='COMPONENT_MANAGER',
      HARDWARE_TYPE='HARDWARE_TYPE', 
      INSTALL='INSTALL', 
      INTERFACE='INTERFACE', 
      INTERFACE_REF='INTERFACE_REF',
      LOCATION='LOCATION', 
      LOGIN='LOGIN', 
      LINK='LINK', 
      LINK_TYPE='LINK_TYPE', 
      NODE='NODE', 
      PROPERTY='PROPERTY',
      SERVICES='SERVICES',
      SLIVER='SLIVER', 
      SLIVER_TYPE='SLIVER_TYPE', 
  )
  
  class RSpecElement:
      def __init__(self, element_type, path):
          if not element_type in RSpecElements:
              raise InvalidRSpecElement(element_type)
          self.type = element_type
          self.path = path
  
subject: set added AVAILABLE and HARDWARE_TYPE elements