offerout amount description [issuer] [label] [absolute_expiry] [refund_for]
Note that it creates two variants of the offer: a signed and an unsigned one (which is smaller). Wallets should accept both: the current specification allows either.
The amount parameter can be the string "any", which creates an offer that can be paid with any amount (e.g. a donation). Otherwise it can be a positive value in millisatoshi precision; it can be a whole number, or a whole number ending in msat or sat, or a number with three decimal places ending in sat, or a number with 1 to 11 decimal places ending in btc.
The description is a short description of purpose of the offer, e.g. withdrawl from ATM. This value is encoded into the resulting offer and is viewable by anyone you expose this offer to. It must be UTF-8, and cannot use JSON escape codes.
The issuer is another (optional) field exposed in the offer, and reflects who is issuing this offer (i.e. you) if appropriate.
The label field is an internal-use name for the offer, which can be any UTF-8 string.
The absolute_expiry is optionally the time the offer is valid until, in seconds since the first day of 1970 UTC. If not set, the offer remains valid (though it can be deactivated by the issuer of course). This is encoded in the offer.
refund_for is a previous (paid) invoice of ours. The payment_preimage of this is encoded in the offer, and redemption requires that the invoice we receive contains a valid signature using that previous payer_key.
On failure, an error is returned and no offer is created. If the lightning process fails before responding, the caller should use lightning-listoffers(7) to query whether this offer was created or not.
The following error codes may occur:
We could also allow multi-use offers, but usually you're only offering to send money once.