Requirements are no longer needed as of 0.9 thanks to the - IF { .. } command, however they are still supported to avoid breaking old scripts. They are written near the top of interact scripts like so:

MyInteractScript:

   Type: Interact
   Requirements:
       Mode: 
       List:
       - FirstReq
       - SecondReq etc. etc.

List of requirements

enchanted, flagged, holding, ingroup, item, isliquid, money, op, owner, permission, ispowered, oxygen, procedure, script, sneaking, storming, sunny, rainy, time, inregion

- enchanted (iteminhand) - flagged [player/npc/global] [<name>([<#>])](:<value>) - holding [<item>] [qty:<#>] [exact] - ingroup (global) [<group>] - item [<item>] (qty:<#>) - isliquid [location:<location>] - money [qty:<#>] - op - owner - permission (global) [<permission>] - ispowered [location:<location>] - oxygen (range:below/equals/above) [qty:<#>] - procedure [<script>] - script [finished/failed] [script:<name>] - sneaking - storming (????????????????????) (This req is ill-defined) - sunny - rainy - time [dawn/day/dusk/night] - inregion [name:<region>]

Denizen/Requirements

List of requirements