^ 1 | Details — A single action in detail. About the action rulebooks

Standard actions which change the state of things
Locking it with , Unlocking it with , Switching on , Switching off , Opening , Closing , Wearing , Taking off

Unlocking something with something (past tense unlocked it with)

Unlocking undoes the effect of locking, and renders the noun openable again provided that the actor is carrying the right key (which must be the second noun).
Unlocking can be performed on any kind of thing which provides the either/or properties lockable, locked, openable and open. The 'can't unlock without a lock rule' tests to see if the noun both provides the lockable property, and if it is in fact lockable: it is then assumed that the other properties can safely be checked. In the Standard Rules, the container and door kinds both satisfy these requirements.
We can create a new kind on which opening, closing, locking and unlocking will work thus: 'A briefcase is a kind of thing. A briefcase can be openable. A briefcase can be open. A briefcase can be lockable. A briefcase can be locked. A briefcase is usually openable, lockable, open and unlocked.'
Inform checks whether the key fits using the 'can't unlock without the correct key rule'. To satisfy this, the actor must be directly holding the second noun, and it must be the current value of the 'matching key' property for the noun. (This property is seldom referred to directly because it is automatically set by assertions like 'The silver key unlocks the wicket gate.')
The Standard Rules provide locking and unlocking actions at a fairly basic level: they can be much enhanced using the extension Locksmith by Emily Short, which is included with all distributions of Inform.

Typed commands leading to this action

"unlock with [something]"

"unlock [a locked lockable thing] with [something]"

"unlock [a lockable thing] with [something]"

"open [something] with [something]"

"open [a locked lockable thing] with [something]"

"open [a lockable thing] with [something]"

Rules controlling this action

check an actor unlocking something with can't unlock without a lock rule
name
unlist 1

A "[regarding the noun][Those] [don't] seem to be something [we] [can] unlock."
name
set

check an actor unlocking something with can't unlock what's already unlocked rule
name
unlist 1

A "[regarding the noun][They're] unlocked at the [if story tense is present tense]moment[otherwise]time[end if]."
name
set

check right second rule
name
unlist 1

A "[The second noun] [do not fit] [the noun]."
name
set

check must be able to reach the key rule
name
unlist

NB: the right second rule is listed instead of the can't unlock without the correct key rule in the check unlocking it with rulebook

carry out unlocking the lockbox with the wide key

carry out unlocking something with a passkey standard passkey unlocking rule
name
unlist

carry out an actor unlocking something with standard unlocking rule
name
unlist

after unlocking the beige door with the thin key

after unlocking the lockbox with the wide key

report someone trying unlocking something with a passkey observe someone unlocking rule
name
unlist

report an actor unlocking something with standard report unlocking rule
name
unlist 2

A "[We] [unlock] [the noun]."
name
set
B "[The actor] [unlock] [the noun]."
name
set

Click on the speech-bubble icons to see the responses, or here to see all of them: 5