I've seen some IM platforms (namely Revolt
and Guilded) have the ability to let the user reference multiple
messages in a single reply, which might be a useful feature. I
think with the XEP as it currently is, it could be fairly simple
to add support for this feature.
I think an addition like this would be
good.
"""
Section 3.2 - Multi-Message Replies
A user may want to reply to multiple
messages with a single message. This can be done by including
many reply elements. Ordering is important, so the reply element
MUST include an "arrangement" attribute that counts up from 0,
with 0 being displayed at the top in the client UI.
EXAMPLE 5. Yuri replies to both Max's and
Anna's messages in a MUC.
```
<message to='knightsguild@muc.example.org'
from='knightsguild@muc.example.org/anna' id='groupchat-id1'
type='groupchat'>
<stanza-id xmlns='urn:xmpp:sid:0' id='groupchat-id1' />
<body>A fort will keep us safe!</body>
</message>
<message
to='knightsguild@muc.example.org'
from='knightsguild@muc.example.org/max' id='groupchat-id2'
type='groupchat'>
<stanza-id xmlns='urn:xmpp:sid:0' id='groupchat-id2' />
<body>Adoring blue flags for style!</body>
</message>
<message to='knightsguild@muc.example.org'
from='knightsguild@muc.example.org/yuri' id='groupchat-id3'
type='groupchat'>
<stanza-id xmlns='urn:xmpp:sid:0' id='groupchat-id3' />
<body>Excellent ideas! Let's get right to
it!</body>
<reply to='knightsguild@muc.example.org/anna'
id='groupchat-id1' arrangement='0' xmlns='urn:xmpp:reply:0'
/>
<reply to='knightsguild@muc.example.org/max'
id='groupchat-id2' arrangement='1' xmlns='urn:xmpp:reply:0'
/>
</message>
```
A fallback for this would work in the same
way as the previous section, the main difference is that the
fallback would include all referenced messages.
"""
I think it also might be worth considering having some kind of
limiter in how many messages can be referenced by one reply -
perhaps MUCs that advertise support for replies could indicate
in a data form how many references may be one message, and if
clients don't self-enforce this, then the MUC could throw a
policy violation error and drop the message.