Suppose we intend a game in which the player needs to cut things open on a regular basis. We'll want to check whether they have the proper tools handy, and deal graciously with commands such as CUT [something] when no tool is specified. So:
{**}Definition: a thing is ripped if the count of rips of it > 0. A thing has a number called the count of rips. After examining something ripped, say "You see [the count of rips of the noun in words] rip[s] in [the noun][if something is in the noun], revealing [a list of things in the noun][end if]."
Moreover, because open containers normally list their contents when examined but we'd prefer Paddington's to be mentioned in the ripping paragraph:
{**}The examine containers rule does nothing when examining the teddy bear.
So far, so good. But suppose that we'd like cutting also to make containers be permanently open and impossible to close again. We could write an "instead" rule, but that would mean that only our instead instructions would take effect, overriding the normal cutting it with rules entirely. Better would be to add a second carry out rule:
Now our rule will occur whenever a container is cut, but play will still go on to the reporting stage. And indeed we can add more of these, of varying degrees of specificity:
For that matter, we might want to add a report rule as well, to occur after the "You slash..." rule, so that every time the player cuts something open which has contents, the contents will be listed.
This time we do not add the condition to the rule (i.e., Report cutting an open noun...) If we did, this report rule would be more specific than the general report rule, and would occur first.
The teddy bear is a closed thing in the Safehouse. The description is "Fluffy[if the head is part of the bear], with an outsized head[otherwise], but headless[end if]." The head is a closed part of the teddy bear. In the bear is a large wad of stuffing. In the head are a small wad of stuffing and a packet of smuggled diamonds.
The quilt is in the Safehouse. The description is "An old but comforting quilt."
Test me with "cut quilt with bear / cut quilt with switchblade / examine quilt / cut bear with switchblade / again / examine bear / cut head with switchblade / get diamonds / mourn loss of innocence".