Is it possible to have a single input or output with multiple addresses I've seen in more than one Blockchain API provider's specs where the transaction inputs and outputs are in the following format:

addresses: ARRAY
The address (or addresses in the case of multi-sig) to which the value was transferred.


I'm confused about the array. When I try these APIs with a transaction where one of the outputs is to a multi sig address, I still see a single multi-sig address in the output.

In which cases would I see multiple addresses in a single output or input?

This the same in these api providers:

https://chain.com/docs#object-bitcoin-transaction

http://dev.blockcypher.com/#transactions

https://toshi.io/docs/#get-transaction
The answer here is escrow outputs.

When one of the outputs is sent to escrow, the related addresses are listed in those arrays.

Here is an example: https://insight.bitpay.com/api/tx/09dd94f2c85262173da87a745a459007bb1eed6eeb6bfa238a0cd91a16cf7790

A single output will be displayed to have multiple addresses.

Blockcypher's API will show an address starting with 4 instead of multiple adresses. And output script type = pay-to-multi-pubkey-hash

{
      "value": 10860,
      "script": "5121032487c2a32f7c8d57d2a93906a6457afd00697925b0e6e145d89af6d3bca330162102308673d16987eaa010e540901cc6fe3695e758c19f46ce604e174dac315e685a52ae",
      "addresses": [
        "4bkHBecr4EQvVUa8Lsa2kH6rGtvsC9AZ5Y"
      ],
      "script_type": "pay-to-multi-pubkey-hash"
    },