Strong vs. Weak Universality

Strong Universality: Any URI/IRI can be used anywhere, anytime, in exactly the same way

Weak Universality: Any URI/IRI can be choosen so that it can be used very widely

Not all URIs/IRIs may be used under all conditions

• Scheme/operation-specific: mailto:, telnet:
• Entry-points: Things simple enough that you want to put them on the side of a bus
• Script-specific IRIs with target audience
• Context-dependent escaping (& => &)
• Identity vs. Resolution