The document discusses summarizing the behavior of a nondeterministic finite state machine (NDFSM) by describing its characteristic function. It notes that to describe the NDFSM in words, one should start by explaining what inputs the machine accepts based on its diagram. It then provides an example characteristic function for a NDFSM that accepts binary strings whose decimal equivalent is divisible by 4. The function states that the language L consists of all strings n such that n is a binary string whose decimal value is always divisible by 4.