After selecting a block of time, you can apply any of the following operations to the highlighted block, thus applying the operation to any keys it contains.
To select time:
A beige bar between two yellow lines appears as you drag across the box grid of the Dope Sheet Key window.
If a highlighted track does not support time operations, time selection in that track is ignored.
After specifying a time range, you can perform other time- and key-related operations.