Rohde & Schwarz MXO38 12bit - and Weird voltage limits at BNC connectors

[Kiriakos GR]

Rohde & Schwarz MXO38 12bit this came out with weird voltage limits, these be printed next to BNC connectors.

This scope has two impedance,  1G Ohm and 50 Ohm.
For the 1G Ohm,  there is printed  <300 RMS and  <400V pk  ( ? )   

For the 50 Ohm, it is specified  < 5V RMS
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I am somewhat prepared so to understand double specifications, because I had recently decode similar specifications over an 100X scope probe.
<400V pk = AC primary component =  <133V RMS AC
<300 RMS = DC primary component  +/- <300V  RMS = DC + ripple component.

< 5V RMS = AC primary component 15V pk or Peak to Peak.