The knock spell will open stuck or held or wizard locked doors. It will also open barred or otherwise locked doors. It causes secret doors to open. The knock spell will also open locked or trick opening boxes or chests. It will loose shackles or chains as well. If it is used to open a wizard-locked door, the knock does not remove the former spell, but it simply suspends its functioning for 1 turn. In all other cases, the knock will permanently open locks or welds — although the former could be closed and locked again thereafter. It will not raise bars or similar impediments (such as a portcullis). The spell will perform two functions, but if a door is locked, barred, and held, opening it will require two knock spells.