Some circuitry gates have special abilities that are called "modes".
Modes allow the gate to have different behaviour without changing its main purpose.
Gate modes include:

• Array modes
  Some gates can accept an array of values instead of a list of inputs.
  This mode is actually beneficial to performance with a large amount of inputs in each object because the gate has to do less processing when working with arrays.


• Customization
  For example "Alarm" has 3 different sounds that can be selected through gate modes.


• Alternative functionality
  Gates like "add" and "multiply" have a special mode where they can accept an array of numbers and multiply each element in that array by some other number, effectively multiplying array by some value.


• Hidden inputs
  Gates can hide one or all of their modes, and activate them when required.
  For example "To String" and "To String Array" gates have a hidden mode that activates when a number is connected to them.
  When that hidden mode is activated, those gates get additional inputs for formatting numbers, such as "truncate" and "max fraction digits"

Using these modes is very simple. All you need is your wiring tool.
Aim at a building, open actions menu (Hold G), and select "Configure object"
Then go to "Modes" tab. This tab contains all modes available for that object (excluding hidden ones).

Each mode has these things:

• Name
• Description
• Icon
• List of inputs and outputs (it is not displayed to the user, but mod developers can modify it in their editor)

Once you decided which mode you want to use, press "Select".
Note that some modes will disconnect all inputs in order to avoid crashing the game!