Global variable are variables which retain their value from one execution of a macro to another.
They are somewhat similar to static variables in C++ or assignable typed constants in Pascal.
By global, it is meant that the list, as any other global variable, will maintain its value, throughout one diary generation, for all tokens of the same macro index. Global variables are not shared between tokens of different macro indices
In the next sections, we will see how Global Variables must be initialized, understand how to take advantage of their scoping rules, cover the precautions that must be followed in using them, and see some examples of their use.