I saw this designation in Trent engines Certificate Datasheets on FAA website.
In Certificate Datasheets, Trent engines designation are followed by 2 digits.
For example (the list below is extracted from FAA Regulatory and Guidance Library) :
RB211-Trent-884B-17
RB211-Trent-892B-17
RB211-Trent-895-17
[...]
RB211-TRENT 970-84
RB211-TRENT 972-84
RB211-TRENT 980-84
[...]
RB211 Trent 553-61
RB211 Trent 556-61
RB211 Trent 560-61
[...]
RB211 Trent 772-60
RB211 Trent 772B-60
[...]
Regards