The name #defined doesn't matter much as long as every header that you will be using together uses a different name. A simple convention like __HeaderName (with _ replacing . in the header's name [sometimes after converting the header's name to uppercase]) is a common convention using namespace that is reserved by the C and POSIX standards for system implementor's use (not application writer's use). If you are writing application code (not part of the system an implementation delivers to customers), you need to choose a naming convention outside of this namespace that is coordinated with code from any other third party vendors whose code may be used with your code. (And if you're writing code you expect other's to use with their own code, you need to document the convention you use so they can avoid naming conflicts when they use your code.) You won't be adhering to the standards, but if you look at your system's headers you can probably easily figure out the conventions used by your OS vendor and use a similar, but slightly different, convention that will be unilkely to conflict with future vendor updates.

The standards reserve namespaces for the standards and namespaces for system implementers; everything else is available to application writers. People who write 3rd party software and end users are both considered "application writers" by the standards. So if you are in that category, you are stuck with finding a naming convention that doesn't trample on the namespace reserved for standards and system implementors (or your code might start behaving in strange ways when the next update to the system software is installed) and is "unique" compared to the namespaces used by other 3rd party code writers and end users.

Talk to the experts at your employer for the language you're using and follow their coding conventions. (Most medium and large sized companies will have these conventions on-line and give new hire programmers a pointer to them as part of their first day on the job "Here's How We Do Things at XYZ Corp." training.)

I will disagree slightly with Corona688 on the version information. If something isn't working for you with code you get from a 3rd party, they may ask for that version number so that can figure out which version of their product you're using. If you expect to ever make changes to headers that you write that will affect programmers using your code, including version information in your headers may save you or your successors many headaches later.