Minimum of parameter value where the default is 1
The behavior of VTE and xterm is the same, all these three commands scroll up by 1 line:
echo -ne '\e[S'
echo -ne '\e[0S'
echo -ne '\e[1S'
ECMA-48 says:
8.3.147 SU - SCROLL UP
Notation: (Pn)
Representation: CSI Pn 05/03
Parameter default value: Pn = 1
SU causes the data in the presentation component to be moved by n line positions [...] where n equals the value of Pn.
Even though the default is 1, it doesn't say the minimum is also 1. According to the specs, if I understand correctly, the explicit value of 0 shouldn't cause scrolling.
Presumably many other escape sequences are affected as well.
I guess changing it would break quite some apps, though...