Scope of registry-- one more thing

[Alex Szalay]

One more thought added/left out:

the intersect function can then be called recursively, if
we do a cross-match among multiple surveys. The final result
is the common area of all the surveys inside the initial
are specified.

Metacode in quasi-C:

AREA aa = ".....";

aa = survey1.intersect(aa,20);
aa = survey2.intersect(aa,20);
aa = survey3.intersect(aa,20);

now aa has the common area of the initial aa and the three
surveys, with our given tolerance.

Cheers, Alex