Terminal Guide

DSR 25 (historically: User Defined Key Status)

ESC1B[5B ?3f 2532 35 n6e
xterm
vte

See below for details:

xterm ( ✔ )

Always replies ESC1b [5b ?3f 232 030 n6e 

historically: unlocked

vte ( ✔ )

Always replies ESC1b [5b ?3f 232 131 n6e 

historically: locked