''trigger_add: <zone>.<variable> | <level> | string/rise/fall/both | //oneshot/reset/<reset level>// :: <command>''

This sets a [[concepts:variables:triggers|trigger]] on a variable

  * **zone** is the zone containing the variable
  * **variable** is the variable to have the trigger added to
  * **level** is the value at which the trigger will fire
  * **string/rise/fall/both** determines if the trigger works with strings, or if it's numeric, at which edge the trigger will fire((i.e. if it's set to fall, it will only fire if the variable's value falls past the trigger value))
  * **oneshot/reset/{reset level}** is an optional field that determines what happens after the trigger has fired - if it's absent, the trigger will need to be rearmed manually; the flag "oneshot" will remove the trigger after firing once; the flag "reset" will cause trigger to go on firing every time the condition is met; placing a value in this field will require the variable to reach this value to re-arm the trigger((this is to provide the option of hysteresis in a the trigger mechanism and prevent over-firing in a noisy system.))
  * **command** is the command to be executed when the trigger is fired