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<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'>All,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'>Can any of you help provide the rationale as to why these
restrictions on services in the current CCSDS TM Space Data Link Protocol book
exist? I am having a difficult time in trying to come up with such a
rationale. Perhaps these restrictions are no longer valid?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'>The text below is copied from section 2.2.4 of the current
CCSDS TM Space Data Link Protocol book:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>Restrictions on Services<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>There are some restrictions on the
services provided on a Physical Channel:<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>a) if the Master Channel Frame
Service exists on a Master Channel, other<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>services shall not exist
simultaneously on that Master Channel;<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>b) on one Master Channel, the
Virtual Channel Operational Control Field<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>Service shall not exist
simultaneously with the Master Channel Operational Control Field Service;<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>c) if the Virtual Channel Frame
Service exists on a Virtual Channel,<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>other services shall not exist
simultaneously on that Virtual Channel;<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>d) on one Virtual Channel, the
Virtual Channel Packet (VCP) Service shall<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>not exist simultaneously with the
Virtual Channel Access Service.<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>thanks and best regards,<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>Greg Kazz<o:p></o:p></span></font></p>
<p class=MsoNormal style='text-autospace:none'><font size=3 face=Arial><span
style='font-size:12.0pt;font-family:Arial'>Chairman CCSDS SLS-SLP WG<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face=Arial><span style='font-size:12.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
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