Wireshark-dev: Re: [Wireshark-dev] Bug 5653 - Display "Day of Year" for January 1 as 1, not 0
From: Guy Harris <[email protected]>
Date: Mon, 7 Feb 2011 10:46:25 -0800
On Feb 7, 2011, at 10:34 AM, Stephen Fisher wrote:

> On Mon, Feb 07, 2011 at 07:52:30AM -0500, Matthew Parris wrote:
> 
>>> Within the abs_time_to_str function, 1900 is added to the tm_year 
>>> parameter, but 1 is not added to the tm_yday.  I'm used to seeing 
>>> the day of the year equal to 1 on January 1st.  Does anyone use 0 
>>> for January 1?
> 
> I agree that changing it to "1" for Jan 1 makes sense from a human 
> reading the screen perspective.

The "day of year" format code was introduced to support a couple of CCSDS:

	http://en.wikipedia.org/wiki/Consultative_Committee_for_Space_Data_Systems

protocols.  The code it replaced displayed the day-of-year as 0-origin; however, this document:

	http://public.ccsds.org/publications/archive/301x0b2s.pdf

speaks of day-of-year as being 1-origin, at least for the ASCII time code formats.

Unless the NASA guys who contributed the packet-ccsds.c and packet-vcdu.c dissectors would like to argue that, in their dissection, a 0-origin day-of-year works better, in which case we should support both 0-origin and 1-origin display formats, I would suggest switching to a 1-origin display format and see whether we get a complaint from any space data people (in which case we should add a separate 0-origin format).