Hi list!

I am proposing to register the following MIME (RFC 2046) media types with the IANA:


bitcoin/psbt

    - aka. a BIP-174 file, in binary
    - does not make any claims about signed/unsigned status; lets leave that to the file

bitcoin/txn

    - aka. wire-ready fully-signed transaction in binary

bitcoin/uri

    - aka [BIP-21](https://github.com/bitcoin/bips/blob/master/bip-0021.mediawiki)
    - could be just a bare bech32 or base58 payment address
    - but can also encode amount, comments in URL args
    - potentially interesting as a response to 402 - Payment required


Other thoughts

- some mime-types are proposed in BIP-71 but those are unrelated to above, and never
  seem to have been registered

- for those who like to encode their binary as base64 or hex, that can be indicated
  as "encoding=hex" or "encoding=base64" in the optional parameters, just like
  "text/plain; encoding=utf-8" does. However, the default must be binary.

- although the above are useful for web servers, they are also useful elsewhere and I
  intend to use them in NFC (NDEF records) where a shorter length is critical.

- I have no idea how easily IANA will accept these proposals.

- current approved mime types: https://www.iana.org/assignments/media-types/media-types.xhtml

Thoughts?

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