Hold Horizontal Angle; Value/Slope - Ruide Theodolite RT-2 User Manual

"HOLD" status. The interval between 2 pressing should not be
more than 3 seconds.

3.3.2 Hold Horizontal Angle

It is used in the circumstances when you need to hold the value of
horizontal angle.
When rotating to a certain degree, press HOLD to freeze the
current horizontal angle value, while a sign of
on the screen. The horizontal angle value will not change no matter
how you rotate.
Press again to disable this function.
Notice: This function is only applicable for horizontal angle.

3.3.3 Value/Slope

Press V/% to shift the display mode of vertical angle between value
and slope.
When the vertical angle is between -45° to 45°，the slope will
display as below.
HOLD will be shown