ATC enroute Controller believes use of temporary altitude information ('T') in data block transfers between ARTCC's is confusing and inappropriate.

Narrative

A new automation procedure between centers has been recently enacted. It allows for interim altitudes to show with a 'T' to the next center. Previous only 'hard' altitudes would display. On the event in question Aircraft X showed on my scope as altitude 390T390. I believed the aircraft was leveling at FL390 as I had traffic at FL 380 (Aircraft Y) opposite direction. Aircraft X came on frequency descending to FL350. FL350 was behind the 'T' and in 'hard' in the flight plan. We displayed FL390. I called the facility who had given me Aircraft X. They acknowledged using FL350 'hard' and 390 interim' and stated they didn't know we showed the 'T' altitudes. This is the third time this has happened and been reported. 'T' times never used to show and were used 'in house' only. They are generally used for planning or a stop gap. I still believe this automation change is unnecessary and undesirable.The ability to show 'T' altitudes to adjacent centers should not be authorized and should be shut off. The negative possibilities far outweigh the few gains.