What is the single code?

The concept of a single code is that the remote control (generally without a display) emits the same infrared code every time the same button is pressed, and only controls a single function code. For example: TV's digital buttons, channel +/- are all single numbers, the function of channel +/-, the remote control itself has no corresponding status, the TV will execute a single (number, channel +/-) after receiving the infrared code function.