I believe this is true.
Examples of cases that should be handled, or guidance should exist:
- An LPR client talks to an LPR printer. You want to replace the printer
with an IPP printer, but can't change the client.
- An LPR printer is absolutely necessary for some purpose, but the client
that used to access it is being upgraded to IPP-only. What to do?
I believe both examples have several solutions, and probably easy ones,
but it's important to keep in mind.
Examples of things that may make trouble are if you paint yourself into
the corner where the client and the server of IPP have to negotiate about
the content type, and there is no "just spray the bits onto the printer;
it worked last week" option, or if you make it a requirement that every
pixel must go onto the page before an acknowledgement can be sent back
to the requester, even though the backend LPR-only printer has internal
storage and no way to show its internal queue.
(My HP Laserjet does that all the time....considerable time passes
between "queue empty" and the time I can fetch the printout....)
Harald A