The drive program calculates the apparent azimuth and elevation
of the sun, it generates the commanded position and it has acces to the
indicated position. These three sets of information are used to determine the
zone of avoidance around the sun.
	The area around the sun is divided into 9 zones. In order to determine
the zones, a lower limit and a upper limit are calculated as a function of
sun's position (+ and - radius in true angles)

	DELSLOW = DELS - RADIUS
	DELSHI  = DELS + RADIUS
and for azimuth
	DAZSLOW = DAZS - RADIUS* either COS(DELSLOW) OR COS(DELSHI)
	DAZSHI  = DAZS + RADIUS* either COS(DELSLOW) OR COS(DELSHI)

ZONES : 1-3  EL < DELSLOW
	1:   AZ  < AZSLOW
	2:   AZSLOW < AZ < AZSHI
	3:   AZ > AZSHI

ZONES : 4-6  DELSLOW < EL < DELSGI
	4:   AZ  < AZSLOW
	5:   AZSLOW < AZ < AZSHI	*** TROUBLE ***
	6:   AZ > AZSHI

ZONES : 7-9  EL > DELSHI
	7:   AZ  < AZSLOW
	8:   AZSLOW < AZ < AZSHI
	9:   AZ > AZSHI

	The current and the final position are zoned; transition between
zones in which one of the coordinate remains higher/lower then the boundary
are no problem. For the other transitions, at least one of the commanded
positions has to be modified until a safe transition can be guaranteed. 
The choice of the transition path might be influenced by the restrictions
imposed by the travel limits.

	Each time the drive program executes it goes through the zoning
anew and thus is not strongly influenced by different rates in azimuth and
elevation. 
	Zone 5 is the zone of avoidance. If the indicated position is ever in
there, it has to be backed out without crossing, and a severe alarm should be
started. If the commanded position is in there, just modify the commanded 
position to go to the closest edge. When tracking (or drifting) it can occur
that the motion of the sun brings the commanded/indicated position into zone 5

	Transitions from zone 1:
No problems into 1,2,3,4 and 7.
	For transitions into zone 6, in general the commanded elevation would
be set to ELSLOW. This would start a transition into zone 2, with similar
restictions into zone 3 and from there the final position can be reached without
danger. If the sun's azimuth is > 180 degrees (thus setting) and the sun's
elevation less than the radius of avoidance + a safety for travel limits etc,
the transition should be forced around the sun going through zones 4,7,8 and 9.
	For transitions into zone 9 the following considerations occur:
If there is a problem with the lower travel limit, use path 4,7,8 and then 9. If
there is the similar problem with the upper travel limit, use 2,3,6 and then 9.
The otherwise preferred route might be 2,3,6 and then 9, especially if the
indicated azimuth is greater than the AZSLOW, otherwise the azimuth direction
would have to be reversed.

	For transitions between 4 and 6: check the travel limit considerations
as in 1. If the choice is free : If both elevations are smaller or larger
than the suns elevation, use the route below ore above respectively. 
In both cases the commanded azimuth and elevation should be set to the corner
from 2-1 or 2-7. If one selects the route above, and once one is above the
elevation of the sun, the actual AZSLOW can be recalculated from the
distance to the sun rather then the corner of the field.