After a ritardando or an accelerando, a score needs a way to say "back to the previous tempo". A tempo is now a marking you can add.

• Insert it from the notation tools and it is drawn above the staff, where a player expects to find it.
• Playback goes back to the tempo in force before the change, so a rit. followed by a tempo sounds the way it reads.
• It survives MusicXML, both ways, so the marking is still there when a score moves between Flat and other notation software.