Sometimes you have the need to type the same thing again and again, such as when typing a dice roll from the chat window. You can recall past messages you've typed in the chat window using the up arrow key. Hitting the up arrow key repeatedly recalls messages farther and farther back in your history. Once you're in this mode, you can use the up and down arrows to cycle backwards and forwards through your chat history.
The up and down arrows don't always recall chat messages from history, however. Here's why. Say you've entered a long message, and now you want to correct something. You hit the up arrow to move the cursor to the word you want to correct and BAM!. If this caused your carefully typed message to be replaced by a one-liner from your history...well, I hate to imagine what you might say about EpicTable. So, if you've typed anything, EpicTable won't recall messages from your history when you hit the up and down arrows.
One more nuance: What if you hit the up arrow to recall a past multi-line message and now you want to edit it? You hit the up arrow...but that recalls the previous message. Never fear. You can still edit a message recalled from your history. Just hit another key before the up or down arrows. For instance, hit the right arrow. That's enough to put the chat window in edit mode rather than history scrolling mode.