temporal event data representation

Start <start> and end <end> are represented as sub class
of events that have <time> tag for representing a time 
instance. Also, <release> and <duetime> are sub classes
of events.

$BFCJL$J;v>]$H$7$F!"#P#S#L#X$G$O!"3+;O(B<start>$B!"(B
$B=*N;(B<end>$B!"%j%j!$l;~9o$r(B
$BI=$7$^$9$N$G!"MWAG$H$7$F(B<time>$B$r;}$A$^$9!#(B

The reason why we don't define new tag like <startTime>
is flexibility for future extension. For example, we may
want to represent "start time just after xxx operation 
is completed." 

$B$7$?$,$C$F!"$?$H$($P3+;O;~9o$O!"0J2pJs$O!"$$$m$$$m3HD%$5$l$k2DG=@-(B
$B$,$"$k$N$G!"#X#M#L$N;EMM$O$3$N$h$&$J%3%s%F%-%9%H$+$i(B
$BFHN)$7$?$b$N$K$7$?$$$N$G$9!#(B
-- 
Yasu Nissy (Yasuyuki NISHIOKA), Dr.Eng.
MIT, 41-211
77 Massachusetts Ave
Cambridge MA 02139
Phone 617-452-2982, Fax 617-253-2249
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