W3C URI Design Principles - slide "Principles: Uniform naming/addressing"

HTML is not the only format: text, PNG, XML, ...
format negotiation: generic URI for several forrmats
HTTP is not the only protocol: ftp, rtp, ...
new protocols can be used for extant names

e.g. proxies
URIs are the only addressing/naming mechanism in the Web
DON´T: make new URI schemes for new data formats