What's the proper format for embedding addresses and keys in QR codes?

[cilphex]

E.g., if you have a public address that is XYZ, do you have the QR code data read as "XYZ" or something like "bitcoin:XYZ"?

I've seen it done both ways and I don't know if there is an actual standard for this or what.  I guess I want to know which kind is more widespread so I can make something more universally compatible.

[Maged]

Well, if it's to make a payment, you would want to use the bitcoin URI, especially since it lets you add things like label and amount. If you aren't displaying the address for the purpose of a payment (such as as a reference to the owner of the address, a la a "bank card"), then the bare address would be better.