def mk_id(field):
  """Builds an identifier from a field.
  """
  name = field.type_id
  if name == "string":
    return "%s" % ("char")
  elif name == "array" and field.size:
    if field.options['fill'].value not in CONSTRUCT_CODE:
      return "%s" % convert(field.options['fill'].value)
    else:
      return "%s" % field.options['fill'].value
  elif name == "array":
    return "%s" % convert(field.options['fill'].value)
  elif name not in CONSTRUCT_CODE:
    return convert(name)
  else:
    return name
Builds an identifier from a field.