An indirect spatial reference is any way to describe a location without
using coordinates. Indirect spatial reference methods usually use a
geographic feature, such as a county, state, township or section of the
Public Land Survey System, or a road, to uniquely identify a place. The
reference may use the name of the feature (for example "Westmoreland
County") or a code that identifies the feature (such as a county FIPS
code). Other examples of indirect spatial references include street
addresses, linear reference systems, and River Reach codes.
Why are indirect spatial references included in the metadata
standards?
Indirect spatial references are included because they are a very common
means by which observations or other attribute information are tied to
a place. The location of many socioeconomic, environmental, and other
data often are referenced by identifying a unit of political geography
(e.g. a city, county, or state), census geography (e.g. block, block group,
or tract), street address, linear referencing system (e.g. milepost),
and so on. While these indirect spatial references alone may not be
sufficient for geographic analyses, they can serve as a means to link
the attribute data to coordinate descriptions of the places to which
the attribute data apply.
Indirect Spatial Reference