W3 Naming Schemes

(See also: a discussion of design issues involved , BNF syntax , W3 background)

The format of a hypertext name consists of the name of the naming sub-scheme to be used, then a name in a format particular to that subscheme, then an optional anchor identifier within the document. For example, the format is for all internet-based access methods:

scheme : // host.domain:port / path / path # anchor

A suffix # anchor id allows one to refer to a particular anchor within a document.

A suffix ? followed by words separated by + signs allows one to seach an index (see details ).

References from one document to another with a similar name may be abbreviated to a relative name . This imposes certain restrictions on the way that the "path" is represented.

A special format is used to represent a search on an index . See also: the full BNF description , about escaping illegal characters .

Examples

file://cernvax.cern.ch/usr/lib/WWW/defaut.html#123

This is a fully qualified file name, referring to a document in the file name space of the given internet node, and an imaginary anchor 123 within it. #greg

This refers to anchor "greg" in the same document as that in which the name appears.

Naming sub-schemes

Different schemes usually use different protocols on the network. The format of the address after the scheme name is a function of the particular scheme. In practice, all internet-based schemes have a common format for the node name and port. Schemes currently defined are as follows, with links to more details.

file

Access is provided to files, using whatever means the browser and/or gateways have to reach files on obscure machines.

news

Access is provided to news articles, and newsgroups, normally using the NNTP protocol.

http

Access is provided to any other information using the HTTP search and retrieve protocol . The internal addressing of the information system is mapped onto a W3 path.

telnet

Access is provided by an interactive telnet session. This is provided ONLY as an interface to other existing online systems which cannot or have not been mapped onto the W3 space.

gopher

Access is provided using the "gopher" protocol. The gopher protocol is similar to HTTP but uses separate concepts of menus and text files rather than hypertext.

wais

Access is provided using the WAIS adaptaion of the Z39.50 protocol.

x500

Format to be defined.

Systems (such as WAIS) which are not currently accessed directly be W3 servers may be accessed though gateways, in which case the document address is encoded within the http address of the document in the gateway. Browsers which do not have the ability to use certain protocols may (in principle) be configured to automaticaly use certain gateways for certain addressing schemes.

This will allow, for example, simple PC-based clients to follow links through X500 name servers.