How special QrCodes are encoded?

I need to create QrCode images (with Google Chart API) that has special QrCode types (like a web link, a Vcard, a PayPal pay button...).

The problem is, I don't find official documents about the string that I should encode. What I did right now, is to follow the raw content of some QrCode Generator on the web. For Example, this is the output for a Web Link QrCode.

http://stackoverflow.com

Here is the encoded string for a phone call

TEL:98989898

So there is special coding and it seems that there are conventions, but I don't find where I can find them.开发者_运维问答 I know I can use the generator to get all the types I need, but I prefer something like a documentation.

The QR code spec does not define a standard for contents. These are examples of de facto standards and standards borrowed from the web.

Here's our best try at summarizing the formats in use: http://code.google.com/p/zxing/wiki/BarcodeContents