Define/include "globally available" arrays and functions

@tomsenner ,

Thank you. Is it ok to declare arrays as a constant? Was the file intended for that?
My array might even change at some point if we add more currencies.

Yes easy to increase and have umpteen new currencies. Also if created in index.php it is globally available same as APPPATH, FCPATH, ROOTPATH, etc

Edit
Why not create a database table from the following CSV file:

https://github.com/datasets/currency-cod...es-all.csv