Serial supports the standard function keys available on a full-size Mac keyboard. The function keys on a MacBook keyboard, however, can only be accessed by pressing the Fn key and then the desired F-key, something that can be difficult to do with one hand. As a convenience, Serial provides command-key shortcuts to make these keys more accessible. The keyboard shortcuts ⌘ + 1 through ⌘ + 0 are equivalent to pressing F1 through F10 respectively.
Serial sends different escape sequences depending on the terminal type selected. If the function keys aren't working properly, you may need to adjust the terminal type on either end of the connection.
When Application Keypad Mode is active (as requested by the device), Serial will treat F1 through F5 as SoftKeys 1 through 5.