What if app has no field for message or tag?

[joakim]

What the title says… not all apps have fields for message and/or tag.

How should an app handle these URIs if it has no fields for entering tags or messages:
iota:MZLFXAZOHO…?tag=important
iota:MZLFXAZOHO…?message=Very%20important%20information

1. Ignore the tag/message?
2. Silently include the tag/message in the transaction, without the user knowing it?

Tough one.

How could the spec prevent this?

Requiring that apps must be able to display tags and messages if provided by the URI is a tall order. It adds extra code and complicates UI, but is the only way to guarantee that the information is not lost or hidden from the user.

A more dev friendly option would be to offer a way out by saying it SHOULD show the tag and message, but if it can't, it MUST inform the user that the message/tag was dropped. That way, at least the user doesn't send information in a transaction without being aware of it.