[dare944]

> No other data structure works like this. You can't mess this up in an array, because no function that manipulates arrays is just going to keep going until there is a null.

This is patently false. Sentinel markers are used widely in array types. Consider GNU's getopt_long() function, a mainstay in GNU tools:

The argument longopts must be an array of [struct option] structures, one for each long option. Terminate the array with an element containing all zeros.