Introduction

The classification part of this standard classifies addresses according to their syntax, that is, their address elements and the order in which the elements are arranged. Syntax determines the record structure needed to hold and exchange an address, and often it is all that is known about the addresses in a given file.

Classifying addresses by syntax rather than semantics (i.e. meaning) allows the users of the standard to focus on record structures, and to avoid making any assumptions about what Address Feature Type the address might identify. Classifying addresses by Address Feature Type can be frustrating or impossible because:

1. Reliable information about an address may be unavailable.
2. Often, one address is used to identify several types of features (e.g., parcel, building, building entrance, utility meter, utility pole, incident location, etc.) at the same location.
3. Address Feature Type categories may be found to be ambiguous or incomplete when applied to a given address.

The classes are presented in four broad groups:

1. Thoroughfare addresses specify a location by reference to a thoroughfare.
2. Landmark addresses specify a location by reference to a named landmark.
3. Postal delivery addresses specify points of postal delivery which have no definite relation to the location of the recipient, such as post office boxes, rural route boxes, overseas military addresses, or general delivery offices.
4. The general address class may include addresses from any or all of the other classes, or addresses whose class is unknown, or whose syntax does not conform to any of the thoroughfare, landmark, and postal classes.

Each class is described by giving its:

1. Name: The name of the class.
2. Syntax: The address elements required and permitted in the class, and the order in which they are arranged.
3. Defining Characteristics: The elements and arrangement that distinguish this class from the other classes.
4. Examples: Illustrative examples of the class.
5. Notes: Explanatory notes about the class.
6. XML Tag: The XML tag for the class.
7. XML Model: XML model of the class.
8. XML Example: The XML model applied to a specific example of the class.
9. XML Notes: Explanatory notes about the XML model.
10. Quality Measures: Data quality tests applied to the class.
11. Quality Notes: Explanatory notes about the data quality meaasures applied to this class.

Syntax and Formatting. The following notation is used to show how classes are constructed from elements:

{} enclose the name of an element.

* indicates that the element is required in addresses of that class. Otherwise the element may be omitted when desired.

+ indicates "and" (concatenation), with a space implied between each component unless stated otherwise.

Example: { Complete Address Number *}+{ Complete Street Name *}+{ Complete Subaddress }

Complex Elements Include All Combinations of Their Component Elements. To avoid a multiplicity of insignificant permutations and combinations, complex elements are used to represent the various combinations of the simple elements that comprise them. Thus, for example, {CompleteAddressNumber} includes all of the following combinations:

1. { Address Number *}
2. { Address Number* } + { Address Number Suffix }
3. { Address Number* } + { Separator Element } + { Address Number Suffix }
4. { Address Number Prefix } + { Address Number *}

Place State ZIP is Shown in Parsed Form. In each class syntax pattern, the Complete Place Name, State Name, Zip Code, Zip Plus 4, and Country Name. are shown separately. They could also be shown in their unparsed form as the Place State ZIP element. However, the elements are shown separately in each syntax pattern, to emphasize the importance of each separate element in the address.

XML Notation and Formatting. XML models and examples conform to the W3 C XML Core Working Group's "Extensible Markup Language (XML) 1.0" (see Appendix A for a complete citation).