WWW World-wide Web, the collection of technologies built up starting with HTML, HTTP, and URIs, the corresponding software (servers, browsers,...), and/or the corresponding content. string identity matching Exact matching of strings, except for encoding duplicates indistinguishable to the user. See section 2. late normalization Each individual component that performs a string identity check has to take equivalences into account. This is usually done by normalizing each string to a preferred representation that eliminates duplicates and ambiguities. Because, with late normalization, normalization is done locally and on the fly, there is no need to specify a web-wide uniform normalization. DOM (Document object model, see http://www.w3.org/DOM/) A series of API definitions to access and manipulate documents, both document structure and textual content. Currently, APIs for basic functionality for HTML and XML, with bindings to programming languages such as Java, ECMAScript, and C. All string parameters in the APIs are defined as Unicode strings. To assure consistent behavior of programs written in different languages and running on different implementations, uniform normalization and string indexing specifications are necessary. early normalization Duplicates and ambiguities are removed as close to their source as possible. This is done by normalizing them to a single representation. Because the normalization is not done by the component that carries out the identity check, normalization has to be done uniformly for all the components of the WWW. character Used in a loose sense to denote small units of text, where the exact definition of these units is still open. uRIs Web addresses, with various components; pivot point for much of the WWW. How to encode arbitrary bytes into a restricted set of characters (using %HH escapes) is well defined, but which character encoding to use to encode arbitrary characters into bytes is not defined. In most cases, e.g. in proxies, comparisons are strictly binary. Without some specification for uniform normalization, some characters cannot reliably be used. Requirements for String Identity Matching and String Indexing 1998-07-10 http://www.w3.org/TR/1998/WD-charreq-19980710 string indexing Indexing into a string to address a character or a sequence of characters. See section 4. RDF (Resource description framework) A data model and streaming format for metadata, with search engines and inference engines as potential users. Much metadata is textual, and a basic operation is to decide whether two elements of metadata are the same or not. For consistent behavior, string identity matching is necessary. UCS Universal Character Set, the character repertoire defined in parallel by [ISO 10646] and [Unicode]. XLL (eXtensible linking language) Linking support for XML. XLL defines the #anchor syntax component of URIs for XML. A syntax for identifying elements in a document tree (e.g. based on element names that can contain arbitrary characters in XML), as well as for identifying portions of text, is defined. For consistent identification of portions of text, either or both of string identity matching and string indexing are necessary.