About custom functions (FileMaker Pro Advanced)The Custom Functions utility lets you create custom functions that can be reused anywhere in the database file in which they are created. You can copy and paste custom functions between FileMaker Pro files or you can import custom functions from other FileMaker Pro files. Once formulas are written for the function, they do not have to be rewritten to be applied to other fields or used in other scripts.
• to replace third-party plug-ins for some purposes