text: from django.db.models import Q
  
  from .choices import InterfaceTypeChoices
  
  
  #
  # Racks
  #
  
  RACK_U_HEIGHT_DEFAULT = 42
  
  RACK_ELEVATION_BORDER_WIDTH = 2
  RACK_ELEVATION_LEGEND_WIDTH_DEFAULT = 30
  
  
  #
  # RearPorts
  #
  
  REARPORT_POSITIONS_MIN = 1
  REARPORT_POSITIONS_MAX = 1024
  
  
  #
  # Interfaces
  #
  
  INTERFACE_MTU_MIN = 1
  INTERFACE_MTU_MAX = 32767  # Max value of a signed 16-bit integer
  
  VIRTUAL_IFACE_TYPES = [
      InterfaceTypeChoices.TYPE_VIRTUAL,
      InterfaceTypeChoices.TYPE_LAG,
  ]
  
  WIRELESS_IFACE_TYPES = [
      InterfaceTypeChoices.TYPE_80211A,
      InterfaceTypeChoices.TYPE_80211G,
      InterfaceTypeChoices.TYPE_80211N,
      InterfaceTypeChoices.TYPE_80211AC,
      InterfaceTypeChoices.TYPE_80211AD,
  ]
  
  NONCONNECTABLE_IFACE_TYPES = VIRTUAL_IFACE_TYPES + WIRELESS_IFACE_TYPES
  
  
  #
  # PowerFeeds
  #
  
  POWERFEED_VOLTAGE_DEFAULT = 120
  
  POWERFEED_AMPERAGE_DEFAULT = 20
  
  POWERFEED_MAX_UTILIZATION_DEFAULT = 80  # Percentage
  
  
  #
  # Cabling and connections
  #
  
  # Console/power/interface connection statuses
  CONNECTION_STATUS_CHOICES = [
      [False, 'Not Connected'],
      [True, 'Connected'],
  ]
  
  # Cable endpoint types
  CABLE_TERMINATION_MODELS = Q(
      Q(app_label='circuits', model__in=(
          'circuittermination',
      )) |
      Q(app_label='dcim', model__in=(
          'consoleport',
          'consoleserverport',
          'frontport',
          'interface',
          'powerfeed',
          'poweroutlet',
          'powerport',
          'rearport',
      ))
  )
  
  COMPATIBLE_TERMINATION_TYPES = {
      'consoleport': ['consoleserverport', 'frontport', 'rearport'],
      'consoleserverport': ['consoleport', 'frontport', 'rearport'],
      'powerport': ['poweroutlet', 'powerfeed'],
      'poweroutlet': ['powerport'],
      'interface': ['interface', 'circuittermination', 'frontport', 'rearport'],
      'frontport': ['consoleport', 'consoleserverport', 'interface', 'frontport', 'rearport', 'circuittermination'],
      'rearport': ['consoleport', 'consoleserverport', 'interface', 'frontport', 'rearport', 'circuittermination'],
      'circuittermination': ['interface', 'frontport', 'rearport', 'circuittermination'],
  }
  