Structures are not the same as arrays is true when you consider that the elements (members for your understanding Andy) can be accessed by a name such as "parameter.whateverAndyWantsToCallIt"
However, the name of a variable of type struct is nothing more than the textual representation of an address and all elements in the structure can be accessed just as an array. Oh, an array name is nothing more than the textual representation of an address.
The C language uses these constructs so that people who have a difficult time seeing memory in their minds can understand data. Unfortunately there are those people who can not look beyond what they were taught in their sophamore year of college and can only represent these items in their strictest definition. I fee for you Andy.

Using the typedef is not necessary.
True, but neither are structures if you are good at programming. Its a style thing Andy and certianly, in my view, more elegant than how you would do it.
Though I susupect my code is written at a level of obfuscation well beyond your comprehension.

Defintion, true it is a definition and not a declaration as the C language demands it. I can't help but think where I would be if it were not for Andy Neil.
Congratulations, you are great at taking a critical look at others. I applaud you!
Allen