The order in which HyperCard passes a message to objects is called the
message-passing order.
Initially, HyperCard sends messages to a specific button or field or to the
current card. If a button or field doesn't handle the message, it goes on to
the current card. From the current card, the message goes to the following
objects, in this order:
* the current background
* the current stack
* the stack script of the Home stack
* HyperCard itself
What happens if an object that receives a message doesn't handle it?
In this case, HyperCard passes the message to other objects and searches
their scripts for a message handler that matches the current message.
This article is adapted from the Claris Tech Info database.