The following definitions are used throughout the documentation:

Table 1. Timer/Counter Definitions
Name Description
BOTTOM The counter reaches BOTTOM when it becomes zero.
MAX The counter reaches MAXimum when it becomes all ones.
TOP The counter reaches TOP when it becomes equal to the highest value in the count sequence.
UPDATE The update condition is met when the timer/counter reaches BOTTOM or TOP, depending on the waveform generator mode.
CNT Counter register value
CCMP Capture/Compare register value

In general, the term “timer” is used when the timer/counter is counting periodic clock ticks. The term “counter” is used when the input signal has sporadic or irregular ticks.