ACL example

acl.json

"owner":{},
"acl": {
  "full": {
    "immutable": true,
    "user_ids": [1,2,4],
    "you": false
  },
  "write": {
    "immutable": false,
    "user_ids": [8,"@user"],
    "any_user": false,
    "you": true
  },
  "read": {
    "immutable": false,
    "user_ids": [],
    "any_user": true,
    "public": false,
    "you": true
  }
},

owner is on the channel itself, as it has wider implications than just ACL (it's a feature of the channel).
public is only on read as it's only applicable there.
any_user is only applicable to read and write.
The groups can have separate immutability, so it is on each one.

If a full access user deletes a message, that message will have is_deleted=true and deleted_by={user_id}.