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<p class="MsoNormal">Hi Lee,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Helps a lot. Thanks for the contribution. I like the "operational domain" idea, that had occured to me as well. The Internet analogy is a local / organizational NTP time server.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Did you guys also explore the different ways to handle clock synchronization on-board?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks, Peter<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">PS – if you can share the "treatise" please do so on the website.<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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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">"Pitts, Robert L. (MSFC-HP27)[HOSC SERVICES CONTRACT]" <robert.l.pitts@nasa.gov><br>
<b>Date: </b>Tuesday, November 6, 2018 at 12:06 PM<br>
<b>To: </b>Peter Shames <Peter.M.Shames@jpl.nasa.gov>, Jon Hamkins <Jon.Hamkins@jpl.nasa.gov>, "sea-time@mailman.ccsds.org" <sea-time@mailman.ccsds.org><br>
<b>Subject: </b>RE: [Sea-time] Existing Time Management BoF charter & supporting material<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D">Actually I do have a treatise but I will spare you.</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D">A few details,</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.25in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">1.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">We did a survey several years ago to assess what level of accuracy and precision is required. We found that the following accuracy/precision characterizes most missions. These were mapped to different phase
of mission where ultra and high were related to measurement activities and coarse to fine were navigational. With navigational related to timescales. </span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<table class="MsoNormalTable" border="0" cellspacing="0" cellpadding="0" style="margin-left:35.25pt;border-collapse:collapse">
<tbody>
<tr style="page-break-inside:avoid">
<td valign="top" style="border-top:double 1.5pt;border-left:double 1.5pt;border-bottom:solid 1.0pt;border-right:solid 1.0pt;border-color:windowtext;padding:0in 5.4pt 0in 5.4pt">
<p class="MsoNormal" style="mso-margin-top-alt:3.0pt;margin-right:0in;margin-bottom:3.0pt;margin-left:0in;text-align:justify">
<span style="font-family:"Arial",sans-serif">Accuracy / Precision</span><o:p></o:p></p>
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<td valign="top" style="border-top:double windowtext 1.5pt;border-left:none;border-bottom:solid windowtext 1.0pt;border-right:solid windowtext 1.0pt;padding:0in 5.4pt 0in 5.4pt">
<ul style="margin-top:0in" type="disc">
<li class="MsoNormal" style="margin-top:3.0pt;margin-bottom:3.0pt;margin-left:-.25in;text-align:justify;mso-list:l0 level1 lfo4">
<span style="font-family:"Arial",sans-serif">Coarse: Millisecond (msec) – 10<sup>-3</sup> sec</span><o:p></o:p></li><li class="MsoNormal" style="margin-top:3.0pt;margin-bottom:3.0pt;margin-left:-.25in;text-align:justify;mso-list:l0 level1 lfo4">
<span style="font-family:"Arial",sans-serif">Fine: Microsecond (μsec) – 10<sup>-6</sup> sec</span><o:p></o:p></li><li class="MsoNormal" style="margin-top:3.0pt;margin-bottom:3.0pt;margin-left:-.25in;text-align:justify;mso-list:l0 level1 lfo4">
<span style="font-family:"Arial",sans-serif">High: Nanosecond (ηsec) – 10<sup>-9</sup> sec</span><o:p></o:p></li><li class="MsoNormal" style="margin-top:3.0pt;margin-bottom:3.0pt;margin-left:-.25in;text-align:justify;mso-list:l0 level1 lfo4">
<span style="font-family:"Arial",sans-serif">Ultra: Picosecond (psec<b>) </b>– 10<sup>-12</sup> sec => (+20 years)</span><o:p></o:p></li></ul>
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</table>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.25in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">2.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">So if you have a number of mission in the Mars arena, why not create a Mars time domain and offer services from infrastructure devices in orbit. Similarly for the Lunar arena. Services could be defined using
multiple techniques. However getting time to all devices within the domain need not be onerous and once in the domain, local relationships to include unique service or relativistic correction would be defined for all local mission. The technique to set time
in the domain would be standard and the services offered would subject to each mission.</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.25in;text-indent:-.25in;mso-list:l1 level1 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">3.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">We also found that there is a need for multiple way to disseminate time. Considerations include:</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.75in;text-indent:-.25in;mso-list:l1 level2 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">a.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">One-way links</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.75in;text-indent:-.25in;mso-list:l1 level2 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">b.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">Low bandwidth links</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.75in;text-indent:-.25in;mso-list:l1 level2 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">c.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">Variable Latency</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.75in;text-indent:-.25in;mso-list:l1 level2 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">d.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">Hop-by-hop transfers</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.75in;text-indent:-.25in;mso-list:l1 level2 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">e.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">Periodic discontinuities</span><o:p></o:p></p>
<p class="MsoListParagraph" style="margin-left:1.75in;text-indent:-.25in;mso-list:l1 level2 lfo2">
<![if !supportLists]><span style="mso-list:Ignore">f.<span style="font:7.0pt "Times New Roman"">
</span></span><![endif]><span style="color:#1F497D">Management of communication link loading</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D">Does this help?</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"><span style="color:#1F497D">Lee</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><b>From:</b> Shames, Peter M (312B) <Peter.M.Shames@jpl.nasa.gov>
<br>
<b>Sent:</b> Tuesday, November 06, 2018 12:45 PM<br>
<b>To:</b> Pitts, Robert L. (MSFC-HP27)[HOSC SERVICES CONTRACT] <robert.l.pitts@nasa.gov>; Hamkins, Jon (JPL-3320)[Jet Propulsion Laboratory] <jon.hamkins@jpl.nasa.gov>; sea-time@mailman.ccsds.org<br>
<b>Subject:</b> Re: [Sea-time] Existing Time Management BoF charter & supporting material<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">Thanks Lee. <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">For the benefit of all of us, could you possibly break down what you mean by "<span style="color:#1F497D">overall distribution and time domains in specific theatres of operation" to a more explicit set of concerns?
Something like a description of what you think "time distribution" and "time domains" mean, and also provide one or more examples of "specific theatres of operation"? We don't need a treatise on the subject (unless you happen to have one at hand), but a little
more detail will help.</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in">Thanks, Peter<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">"Pitts, Robert L. (MSFC-HP27)[HOSC SERVICES CONTRACT]" <<a href="mailto:robert.l.pitts@nasa.gov">robert.l.pitts@nasa.gov</a>><br>
<b>Date: </b>Tuesday, November 6, 2018 at 10:28 AM<br>
<b>To: </b>Peter Shames <<a href="mailto:Peter.M.Shames@jpl.nasa.gov">Peter.M.Shames@jpl.nasa.gov</a>>, Jon Hamkins <<a href="mailto:Jon.Hamkins@jpl.nasa.gov">Jon.Hamkins@jpl.nasa.gov</a>>, "<a href="mailto:sea-time@mailman.ccsds.org">sea-time@mailman.ccsds.org</a>"
<<a href="mailto:sea-time@mailman.ccsds.org">sea-time@mailman.ccsds.org</a>><br>
<b>Subject: </b>RE: [Sea-time] Existing Time Management BoF charter & supporting material</span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D">Jon and Peter,</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D">I think you are hitting on the areas that I am most concerned with to include overall distribution and time domains in specific theatres of operation.</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D">Lee</span><o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"><span style="color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"><b>From:</b> SEA-TIME <<a href="mailto:sea-time-bounces@mailman.ccsds.org">sea-time-bounces@mailman.ccsds.org</a>>
<b>On Behalf Of </b>Shames, Peter M (312B)<br>
<b>Sent:</b> Tuesday, November 06, 2018 12:16 PM<br>
<b>To:</b> Hamkins, Jon (JPL-3320)[Jet Propulsion Laboratory] <<a href="mailto:jon.hamkins@jpl.nasa.gov">jon.hamkins@jpl.nasa.gov</a>>;
<a href="mailto:sea-time@mailman.ccsds.org">sea-time@mailman.ccsds.org</a><br>
<b>Subject:</b> Re: [Sea-time] Existing Time Management BoF charter & supporting material<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">Hi Jon,<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">Good questions. As we have been addressing time synchronization that topic explicitly includes automated means doing this, especially in a multi-mission, networked (DTN), context. I think of it as NTP for DTN.
This is a substantially bigger topic than a simple addition of an offset.<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">Do the rest of you agree?<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in">Thanks, Peter<o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
<p class="MsoNormal" style="margin-left:1.0in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Jon Hamkins <<a href="mailto:Jon.Hamkins@jpl.caltech.edu">Jon.Hamkins@jpl.caltech.edu</a>><br>
<b>Date: </b>Tuesday, November 6, 2018 at 8:34 AM<br>
<b>To: </b>Peter Shames <<a href="mailto:Peter.M.Shames@jpl.nasa.gov">Peter.M.Shames@jpl.nasa.gov</a>>, "<a href="mailto:sea-time@mailman.ccsds.org">sea-time@mailman.ccsds.org</a>" <<a href="mailto:sea-time@mailman.ccsds.org">sea-time@mailman.ccsds.org</a>><br>
<b>Subject: </b>Re: [Sea-time] Existing Time Management BoF charter & supporting material</span><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Thanks, Peter.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">The IOAG Service Catalog requests the following standards be developed:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">• Clock Correlation Procedures [CC] - Magenta Book<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">• Time Transfer [TT] - Blue Book<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">• Time Synchronization [TS] - Blue Book<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Do we all agree that these are still the appropriate books and colors to
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">be working toward? Do we need to update our goals? Thoughts?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">On a separate topic, I have been thinking about what we discussed in
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Berlin. We mentioned time correlation and time synchronization as two
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">motivations for the work. As we discussed, time correlation is
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">determining the offset between two clocks, and time synchronization is
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">setting two clocks so that they match. The difference between these
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">concepts is quite small -- a time synchronized clock output is simply
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">the time correlated clock output time plus the value of the offset. In
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">other words, after time correlation, a time offset is determined.
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Whether this offset is used to explicitly synchronize a clock or is
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">simply added to the clock output each time it is read is an
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">implementation detail. For this reason, I recommend that going forward,
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">we consider time correlation and time synchronization to be
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">fundamentally the same concept, with the same time correlation standard
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">governing them.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> ----Jon<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">On 11/5/2018 5:21 PM, Shames, Peter M (312B) wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Dear Time BoF,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Attached is the current draft of the Time WG Charter and also the IOAG
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">Service catalog #2. See pgs 26-27, section 4.5, to see what it is that
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">the IOAG has requested. There is also an existing set of materials
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">relating to this topic that Ed Greenberg developed.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">_______________________________________________<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in">SEA-TIME mailing list<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"><a href="mailto:SEA-TIME@mailman.ccsds.org">SEA-TIME@mailman.ccsds.org</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"><a href="https://mailman.ccsds.org/cgi-bin/mailman/listinfo/sea-time">https://mailman.ccsds.org/cgi-bin/mailman/listinfo/sea-time</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:1.5in"> <o:p></o:p></p>
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