Samsung SyncMaster 400TSN User Manual page 105

Specifications
Horizontal Frequency
The time to scan one line connecting the right edge to the
left edge of the screen horizontally is called the Horizontal
Cycle and the inverse number of the Horizontal Cycle is
called the Horizontal Frequency. Unit: kHz
Vertical Frequency
Like a fluorescent lamp, the screen has to repeat the same
image many times per second to display an image to the
user. The frequency of this repetition is called the Vertical
Frequency or Refresh Rate. Unit: Hz