In most operating systems, including Mac OS, pressing Option + Arrow Key permits to jump from word to word. Strictly speaking, this command jumps to the next non-word character. I am assuming there is a definition somewhere in the operating system that governs which characters the cursor will jump to (e.g., a regular expression or definition of which set of characters form the set of non-word characters).
I would like to modify this definition. When I edit a file name like '123_Name_Date.txt' on pressing Option + → the cursor will jump from the beginning of the file name directly to the full stop. I would, however, like it to consider the underscore a non-word character to stop at, too.
So, can I modify or extend the list of characters that Mac OS considers stop-characters in cursor skipping? If so, where and how?