From ITU-T G.992.5:
Systems support a net data rate ranging up to a minimum of 16 Mbit/s downstream and 800 kbit/s upstream. Support of net data rates above 16 Mbit/s downstream and support of net data rates above 800 kbit/s upstream are optional.
Since Annex M deals with "Specific requirements for an ADSL system with extended upstream bandwidth", this would in turn mean that plain G.992.5 only supports 800 kBit/s.
As for Annex A, there is a whitepaper that shows ~1.1 MBit/s as actual data rates, which is similar to what other sources report.
My assumption is that actual data rates were not explictly defined in G.992.5.