What is the meaning of a traffic police officer raising one arm straight up as a signal?

At Article 7 of the National Technical Regulation QCVN 41:2019/BGTVT (effective from July 1, 2020). To be specific:

The hand raised vertically signals that all participants in traffic from all directions must stop;

=> Thus, according to the above regulation, when the traffic police or traffic controller raises their hand vertically, it means that the signal for traffic participants from all directions must stop.

Additionally, the Regulation also stipulates:

Both hands or one hand extended horizontally signals that traffic participants in front of and behind the controller must stop; traffic participants on the right and left of the controller are allowed to proceed in all directions; the left arm of the controller bends back and forth behind the neck to signal the traffic participants on the left side of the controller to go faster or the right arm of the controller bends back and forth in front of the chest to signal the traffic participants on the right side of the controller to go faster; the left or right hand of the controller at waist level, moving up and down signals traffic participants on the left or right side of the controller to slow down; the left or right hand of the controller raised vertically perpendicular to the ground signals traffic participants on the left or right side of the controller to stop;

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