Professional issues
For professional purposes, field-based numbering is the recommended method: you have complete control and it never breaks.
However, it is impracticable, and thus silly, to introduce field-based numbering into the corporate workplace. It's years since corporations stopped providing word-processor training for their staff. Even if they were to do so, the Microsoft Word training available these days is so simplistic that it never gets anywhere near the professional-level features of Word such as field-based numbering. You should not expect corporate users to understand Word well enough to use field-based numbering. So you should very definitely expect a disaster if you send such people a document containing it: you will certainly get one.
I did not leave the numbering samples in this FAQ as Word numbering to send to you: I can't because I have no idea how the numbering will appear when you look at it: the numbering can change dramatically when your computer applies your local preferences to it. I prepared the example in Word 2000, then saved it in Word 2 for Windows format, closed it and re-opened the file. This is the simplest way to strip the numbering back to ordinary typed text that won't change no matter where you display it.
This is a major issue in Word numbering, and is the reason that corporations are reluctant to roll out the higher levels of Word (97, 98, 2000, 2001, 2002). The numbering is simply not transportable from user to user, machine to machine, or office to office. Since that is a fundamental requirement for corporate documents, many large corporations have gone no further than Word 97. Others have rolled back to WordPerfect 9. As yet, there are no alternatives we can offer you, other than the fix covered in How to cure Word's List Numbering with a dose of VBA).