Our documentation doesn't say much else:
• TO – takeoff
• TO 1 – derated takeoff one
• TO 2 – derated takeoff two
• D-TO – assumed temperature reduced thrust takeoff
• D-TO 1 – derate one and assumed temperature reduced thrust takeoff
• D-TO 2 – derate two and assumed temperature reduced thrust takeoff
There are planes with different annunciations though:
• R-TO – reduced takeoff
• R-CLB – reduced climb
Note: R-TO does not indicate the type of reduced takeoff. The N1 limit may be reduced due to the entry of an assumed temperature, a takeoff thrust derate or a combination of both assumed temperature and takeoff thrust derate.