There is a need to express geospatial "bounding box"
searches using the Common Query Language (CQL) syntax.
In the PQF used with YAZ and Z39.50 attributes, this
is an example of such a search:
find @attr 1=2060 @attr 2=7 @attr 4=201 "36.5 -106.7 25.8 -93.5"
In this example:
@attr 1=2060 refers to Use Attribute 2060,
Bounding Coordinates
@attr 2=7 refers to Relation Attribute 7,
Overlaps
@attr 4=201 refers to Structure Attribute 201,
Coordinate String
"36.5 -106.7 25.8 -93.5" contains North West South East
coordinates (i.e, Texas area)
As pointed out by Rob, the CQL context set defines
"within/partial" as semantically equivalent to the
"Overlaps" Relation Attribute.
In the GILS, Geo and Bio CQL context sets, the word
"bounds" could be used for the "Bounding Coordinates"
Use Attribute.
Also, "nwse" could be used for the "Coordinate String"
Structure Attribute. (This has the great advantage of
making obvious the order of lat/lon coordinates.)
Using these recommendations and my example search,
I guess the CQL expression for a "bounding box"
geospatial search would be like this:
bounds within/partial/nwse "36.5 -106.7 25.8 -93.5"
Is that correct?
Eliot
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