Issue in Behavior of Interval Datatype

select (interval '56:48' minute to second);
result：00:56:48
select (interval '-56:48' minute to second);
result：-56:48:00
select (interval '+56:48' minute to second);
result：56:48:00

When user uses ‘+’ or ‘-‘ symbol, then minute to second range is getting
ignored.

I have checked the code and found that in function DecodeInterval(), for
timezone case (DTK_TZ) it uses INTERVAL_FULL_RANGE irrespective of range
passed by user.

However if use the range passed as argument in function DecodeInterval(),
the result of using ‘+’ or ‘-‘ is same as without using it.

Is there any particular reason for ignoring the range for DTK_TZ case in
DecodeInterval() function?

With Regards,

Amit Kapila