Not sure if that is entirely accurate for the AC units, It's easy to come across data for the 4200 but quite hard for the 4200A
Seems from what I have found so far is that the 4200 will go up to 1000V without any extra option fitted, the user manual on K04BB mentions only 2 options for the 4200 (ignoring options for things like rack mounting, mains voltage etc).
Option 30 - AC Current to 2 A
Option 41 - Rear Output
But for the 4200A for 1000V it must have Option 10 or it is limited to 200V
Option 10 - 1000V Range
Option 30 - AC Current to 2 A
Option 42 - RearOutput