  # Header encoding (see RFC5987)
  HTTP_HEADER_ENCODING = 'iso-8859-1'
  
  # Default input and output format
  ISO8601 = 'iso-8601' 
</s> remove         ISO8601,
 </s> add         ISO_8601, </s> remove     'DATE_OUTPUT_FORMAT': ISO8601,
 </s> add     'DATE_FORMAT': ISO_8601, </s> remove     'TIME_OUTPUT_FORMAT': ISO8601,
 </s> add     'TIME_FORMAT': ISO_8601, </s> remove from rest_framework import ISO8601
 </s> add from rest_framework import ISO_8601 </s> remove         self.output_format = output_format if output_format is not None else self.output_format
 </s> add         self.format = format if format is not None else self.format
  # Header encoding (see RFC5987)
  HTTP_HEADER_ENCODING = 'iso-8859-1'
  
  # Default input and output format

keep keep keep keep replace
 Clean ups to datetime formatting 
rest_framework/__init__.py