[sv-ec] 890 scheduling algorithm questions

The sv-cc discussed the 890 scheduling algorithm picture today and
Michael Rohleder asked the following questions:
 
1) There is a loop back to the active region from the pre-NBA, NBA and
post-NBA 
regions. This presumes that when a PLI callback wakes up in the pre-NBA
region for ex,
the pli user code may schedule an event into the active region queue.
The interpretation from the picture lead us to understand that if that
it is the case (an event 
has been scheduled from the pli pre-NBA region in the active region),
the active region queue
is processed once the pre-NBA events have been processed, before moving
to processing the NBA region
events.
 
Michael wants to get the confirmation that this is the correct
interpretation and that has not changed since 1364.
 
2) same issue for the loop back for the NBA and post-NBA regions
 
3) There is a loop back from the observed and post-observed regions to
the active region
There is no loop back from the pre-observed to the active region and the
text explicitly states that it is illegal to write
values or schedule an event from that region:
9.3.3.5 Pre-Observed region

"it is illegal to write values to any net or variable or to schedule an
event within

the current time slot."

Why this discrepancy?
If those regions are "read only" as the text states , why is there a
loop back to active?
Extract from mantis 890:

9.3.2.5 Observed events region

The Observed region is for evaluation of property expressions when they
are triggered.

During property evaluation, pass/fail code shall be scheduled in the
Reactive region of

the current time slot. PLI callbacks are not allowed in the Observed
region.

9.3.3.6 Post-Observed PLI region

The Post-Observed region provides for a PLI callback control point that
allows PLI

application routines to read values after properties are evaluated (in
the Observed or an

earlier region).

 
Francoise
       '

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