Hi.

I have an idea that subject.

There are already BIP 21.
But Multisig request URI is non exist.

My idea is below:

bitcoin-sigreq://{{rawtx}}?{{param}}

rawtx: raw transaction (encoded by base64)
param:
- pubkey={{public key for sign key pair}}
- hd_wallet_position={{path for HD wallet position}}

This URI scheme is used for multisig request from website to user's local
wallet.

How do you think ?