DCMI Box Encoding Scheme
Creators: 
Simon Cox

Contributors: 
Andy Powell
Andrew Wilson Pete Johnston 
Date Issued:  20060410 
Latest Version:  https://dublincore.org/specifications/dublincore/dcmibox/ 
Release History:  https://dublincore.org/specifications/dublincore/dcmibox/release_history/ 
Description:  The DCMI Box encoding scheme is a method for identifying a region of space using its geographic limits and representing that information as a value string. Components of the value string correspond to the bounding coordinates in north, south, east and west directions, plus optionally up and down, and also allow the coordinate system and units to be specified, and a name if desired. A method for encoding DCMI Box in a text string using the DCSV syntax is described. This notation is intended for representing a value of the DCMES element Coverage, particularly when using HTML meta elements. 
Table of Contents

 Introduction

 Identifying a place  the DCMI Box scheme

 Encoding DCMI Box with DCSV syntax

 Examples

 References
1. Introduction
Several methods are available to indicate a place. These include, but are not limited to:
 a name , normally defined in an identifiable enumeration such as a gazetteer or list of jurisdictional localities;
 a unique geocode , such as a postal code;
 the coordinates of a point , using geographic values or some welldefined projection and units;
 a set of arcs or faces describing the polygon or polyhedron comprising the perimeter of the place;
 the limits of a regular shaped container which encompasses the place, typically a rectangular box in two or three dimensions, using geographic values or some welldefined projection and units.
The Dublin Core™ Metadata Element Set [DCMES] includes an element, Coverage , the value of which may be a place. If a name or geocode is used as the value representation for the property, then the enumeration from which that is selected determines valid value strings. However, there are no simple, commonly used, notations for indicating a place using coordinates. Here we define DCMI Box, an encoding scheme which specifies the geographic limits of a place, and describe a method for encoding DCMI Box in a text string using the DCSV syntax [DCSV].
In the simplest usage, DCMI Box approximates the extent of a place using a container with a regular shape. For a more precise representation of an irregular shape it is possible to use the approach of "tiling" the place with a set of simple regions defined using DCMI Box. Alternatively, another notation describing a polygon or polyhedron may be used. If a value corresponding to a point is required, then DCMI Point [POINT] is available.
2. Identifying a place  the DCMI Box scheme
We identify a place by considering the minimal rectangular box which fully encloses the place, whose faces are aligned parallel with the axes of an identified cartesian coordinate system [Figure].
We define the following components to describe the box:
Component Label  Definition  Default Component Value^{1} 

northlimit  The constant coordinate for the northernmost face or edge^{2}  INF^{3} 
eastlimit  The constant coordinate for the easternmost face or edge^{2}  INF^{3} 
southlimit  The constant coordinate for the southernmost face or edge^{2}  INF^{3} 
westlimit  The constant coordinate for the westernmost face or edge^{2}  INF^{3} 
uplimit  The constant coordinate for the uppermost face or edge^{2}  INF^{3} 
downlimit  The constant coordinate for the lowermost face or edge^{2}  INF^{3} 
units  The units applying to unlabelled numeric values of northlimit, eastlimit, southlimit, westlimit  signed decimal degrees 
zunits  The units applying to unlabelled numeric values of uplimit, downlimit  metres 
projection  The name of the projection used with any parameters required, such as ellipsoid parameters, datum, standard parallels and meridians, zone, etc  geographic coordinates on Earth for northlimit, eastlimit, southlimit, westlimit; height above meansealevel for uplimit, downlimit 
name  A name for the place^{4}   
**^{1}***All components are optional. If any *limit component is absent, then this implies an interval unbounded on that side. Thus, a DCMI Box with a single component northlimit="0" would identify the entire southern hemisphere._
**^{2}***Component values are text strings representing numbers. Units should be included using conventional (SI) notation, unless the relevant units or zunits component is present. However, if units are given as part of any component value, then for this component these override those given by units or zunits._
**^{3}***If this component is absent then the value is undefined. Processors performing numeric comparisons are recommended to set values corresponding to maximally inclusive matching._
**^{4}***In this context the name is nonnormative. In the case of a conflict, the place identified by the coordinate values takes precedence. The name is provided for user convenience only._
3. Encoding DCMI Box with DCSV syntax
The components specified above have no meaning when disaggregated, since in any particular instance it is the complete set which acts to indicate the specific location. For systems in which data is encoded using a limited character set, this is conveniently accomplished by packaging the components into a single text string according to the DCSV syntax [DCSV].
A DCMI Box value string using DCSV syntax, and using the component names defined above, appears as follows:
northlimit=v1; eastlimit=v2; southlimit=v3; westlimit=v4; uplimit=v5; downlimit=v6; units=v7; zunits=v8; projection=v9; name=v10
where v1  v10 are component values as defined in the table above.
All components are optional but must not be repeated, and their order is not significant.
4. Examples
Western Australia:
name=Western Australia; northlimit=13.5; southlimit=35.5; westlimit=112.5; eastlimit=129
Lake Jindabyne:
northlimit=5980000; westlimit=644000; eastlimit=647000; southlimit=5966000; units=m; projection=UTM zone 55 south
The Western Hemisphere:
westlimit=180; eastlimit=0
The Tropics:
northlimit=23.5; southlimit=23.5
A mine, illustrating the use of 3D coordinates:
northlimit=21.3; southlimit=21.4; westlimit=139.8; eastlimit=139.9; uplimit=400; downlimit=100; name=Duchess copper mine
5. References
[DCMES]
Dublin Core™ Metadata Element Set, Version 1.1: Reference Description,
http://dublincore.org/specifications/dublincore/dces/.
[POINT]
DCMI Point Encoding Scheme,
http://dublincore.org/specifications/dublincore/dcmipoint/.
[DCSV]
DCMI DCSV: A syntax for representing simple structured data in a text string,
http://dublincore.org/specifications/dublincore/dcmidcsv/.