anchor.diff:  	{_, PAlterSTimeISO} = lists:keyfind("startDateTime", 1, PAlterVF),
   	case lists:keyfind("endDateTime", 1, PAlterVF) of
   		false ->
  -			{ocs_rest:timestamp(PAlterSTimeISO), undefined};
  +			{ocs_rest:iso8601(PAlterSTimeISO), undefined};
   		PAlterETime ->
  -			{ocs_rest:timestamp(PAlterSTimeISO), PAlterETime}
  +			{ocs_rest:iso8601(PAlterSTimeISO), PAlterETime}
   	end;
   prod_price_alter_vf(json, PAlter) ->
   	ValidFor = PAlter#alteration.valid_for,
  
positive.code: 	Descirption = prod_description(json, Prod),
  	Href = prod_href(json, Prod),
  	ValidFor = prod_vf(json, Prod),
  	IsBundle = prod_isBundle(json, Prod),
  	Name = prod_name(json, Prod),
  	Status = prod_status(json, Prod),
  
negative.code: 	{_, {struct, VFObj}} = lists:keyfind("validFor", 1, Product),
  	{_, SDT} = lists:keyfind("startDateTime", 1, VFObj),
  	{_, EDT} = lists:keyfind("endDateTime", 1, VFObj),
  	{ocs_rest:iso8601(SDT), ocs_rest:iso8601(EDT)};
  prod_vf(json, Product) ->
  	case Product#product.valid_for of
  		{SDateTime, undefined} ->
  