Update index.md

content/commands/ts.incrby/index.md

@@ -149,6 +149,8 @@ is the policy for handling duplicate samples. A new sample is considered a dupli
   - The difference of the current timestamp from the previous timestamp (`timestamp - max_timestamp`) is less than or equal to `IGNORE_MAX_TIME_DIFF`;
   - The absolute value difference of the current value from the value at the previous maximum timestamp (`abs(value - value_at_max_timestamp`) is less than or equal to `IGNORE_MAX_VAL_DIFF`.
 
+where `max_timestamp` is the timestamp of the sample with the largest timestamp in the time series, and `value_at_max_timestamp` is the value at `max_timestamp`.
+
 When not specified: set to the global [IGNORE_MAX_TIME_DIFF]({{< baseurl >}}/develop/data-types/timeseries/configuration#ignore_max_time_diff-and-ignore_max_val_diff) and [IGNORE_MAX_VAL_DIFF]({{< baseurl >}}/develop/data-types/timeseries/configuration#ignore_max_time_diff-and-ignore_max_val_diff), which are, by default, both set to 0.
 
 These parameters are used when creating a new time series to set the per-key parameters, and are ignored when called with an existing time series (the existing per-key configuration parameters is used).