What limitation exists regarding the use of macros?

The limitation regarding the use of macros is that they cannot be called within another macro. This is an important aspect of macro functionality because it ensures that each macro operates independently without nesting, which can complicate execution and debugging. By keeping macros standalone, the system maintains clarity and simplicity in the code structure. This prevents potential recursion issues and makes the logic flow easier to follow, thereby reducing the chances of errors occurring during execution.

In contrast, the other options suggest limitations that do not align with how macros are typically implemented. For example, macros can be reused multiple times throughout a project, and they are not restricted to specific data types or limited to only operating on numerical data. They are generally versatile and can handle various data types depending on how they are defined, providing users with a lot of flexibility in their applications.