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This note summarizes the changes in gluex doc 1799 since it was
first posted. To leading order, it adopts all of the changes
proposed by Paul Mattione and David Lawrence, with some
modifications. Read on for the details.<br>
<br>
<br>
Draft 2 changes to the MC dst format since draft 1:<br>
<ol>
<li><b>reaction (MC info header)</b> - removed "type", was
included in case a Monte Carlo generator wanted to distinguish
different types of reactions being merged together in the event
stream. We do not use this, and I don't foresee any demand for
it.</li>
<li><b>vertex</b> - made clear that this is a list, whose average
length for the benchmark MC sample used to meter the record size
happens to be 1. Added a unique "id" element for each vertex in
the list, which is the referent of "vertexID" in the product
section.</li>
<li><b>product </b>- took out the "pdgtype" field because it is
redundant with the PID field, now renamed to "ptype". Other
field have been renamed, to better respect the rule that the
keyword "id" indicate a relational handle. This invented rule
only applies to this document.</li>
<li><b>tagger hits</b> - made it explicit that this is a list of
hits, and not just one, although current simulations feature
only one per event. Added a field for "id" in anticipation of
kinematic fits objects we hope to add shortly that refer to a
tagger hit. Added a field for "time" (thanks David) but not for
uncertainties. Tagger energy uncertainties are too small to
care about (3-5 MeV rms) and the time resolution will be a
calibration db constant (or array) not a per-event quantity.
Right now it is unsmeared (zero error) in the simulation.</li>
<li><b>neutrals</b> - renamed this section DNeutralShowerCandidate
(thanks Paul) to indicate the reconstruction object that it
recapitulates. The one difference between ours and the proposal
for this section by Paul Mattione is the length of the
"correlations" array. We think there should be 3 off-diagonal
matrix elements for Bcal showers and 2 for the Fcal. Space is
left for 3. I will follow up this message with a new email
detailing our arguments for this.<br>
</li>
<li><b>charged tracks</b> - renamed this section
DChargedTrackHypothesis (thanks Paul) to indicate the
reconstruction object it recapitulates. Here I pretty much
carried over everything from Paul's proposal, which looks
cleaner than our original one, and complete. Thanks to David
for clarifying exactly what the "projected time" meant. We
changed some of the names to ones that better represent the
meaning of the variables, we think.</li>
</ol>
-Richard Jones<br>
(for Igor S. and rtj)<br>
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