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<p class="MsoNormal">John,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I realize you are on vacation, but when you come back$B!D(B<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">As part of the ESTRACK/DSN schedule exchange work ongoing, a question about time representation has arisen. I have taken a look and my conclusion is that the schema that we have for Time code B does not quite match the Time code B definition
in the book. Certainly a more "relaxed" definition with regard to sub seconds is in order for reporting things like schedules which often (although perhaps not exclusively) don't need anything stated below a second resolution.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Here is what the CCSDS recommendation on Time codes says about T.C. B says about it:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">$B!H!D(B.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">3.5.1.2 ASCII TIME CODE B, Year/Day of Year Calendar Variation:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">The format for ASCII Time Code B is as follows:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">YYYY-DDDThh:mm:ss.d$B"*(BdZ<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">where each character is an ASCII character using one octet with the following meanings:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">YYYY = Year in four-character subfield with values 0001-9999<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">DDD = Day of year in three-character subfield with values 001-365 or -366<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">T = Calendar-Time separator<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">hh = Hour in two-character subfield with values 00-23<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">mm = Minute in two-character subfield with values 00-59<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">ss = Second in two-character subfield with values 00-59<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">(-58 or -60 during leap seconds)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">d$B"*(Bd = Decimal fraction of second in one- to n-character subfield<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">where each d has values 0-9<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">Z = time code terminator (optional)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">The hyphen (-), colon (:), letter $B!F(B T$B!G(B and period (.) are used as specific subfield separators,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">and that all subfields must include leading zeros.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">As many $B!F(Bd$B!G(B characters to the right of the period as required may be used to obtain the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">required precision.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">An optional terminator consisting of the ASCII character $B!F(BZ$B!G(B may be placed at the end of the<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">time code.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">EXAMPLE: 1988-018T17:20:43.123456Z<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Times New Roman",serif">$B!D(B.$B!I(B<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">And here is the key line in the XML schema that defines the pattern<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><xsd:pattern value="\d{4}-\d{3}T\d{2}:\d{2}:\d{2}\.\d+Z?"/><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Note that the CCSDS book says $B!H(B..As many $B!F(Bd$B!G(B characters to the right of the period as required may be used to obtain the<o:p></o:p></p>
<p class="MsoNormal">required precision$B!I(B. I take this to mean that $B!H(Bas many$B!I(B could in fact be 0 (zero).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Given that, I think the XML schema line should read:<o:p></o:p></p>
<p class="MsoNormal"><xsd:pattern value="\d{4}-\d{3}T\d{2}:\d{2}:\d{2}\.\d*Z?"/><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">With this definition which I think is consistent with the definition of Time code B implementations are not required to state at least a 10<sup>th</sup> of a second for timestamps.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I propose that we update the schema accordingly which I think makes the schema more useful to our implementing organizations, consistent with time code B definition, while still allowing for the subsecond expression if needed.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Best regards,<o:p></o:p></p>
<p class="MsoNormal">-Erik<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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