SEEK

Because the language used for querying ecogrid nodes can only compare fields to
constants:

<condition operator="LESS THAN" concept="westBoundary">-23.0</condition>

it's possible for records whose bounding coordinates cross the International
Date Line to be returned when they shouldn't be and to not return when
circumstances dictate that they should.

In order to construct a query to correctly handle such records, a means is
needed to compare a field to another field within a record (e.g. westBoundary >
eastBoundary).