…heading numbering would by default include all previous levels of numbering.
What does that mean? Here’s an example of heading numbering (this is BAD, and is used by US government documents like the CFR):
1. This is heading 1
a. This is heading 2
b. Heading 2 again
i. This is heading 3
A. This is heading 4
2. Heading 1 again
a. Heading 2 yet again
Body text example.
i. Heading 3 again
ii. Heading 3 yet again
The problem here is figuring out the absolute reference for the ‘Body text example’. It’s under a), OK. But what is that under? In this small example you can easily see that it’s under 2. So the example is 2a).
But if section 2 started several pages before, you would have to flip back and find what the previous level was. You might miss it, and get the wrong reference. It’s a pain.
This is a better solution – include the previous levels in each heading number:
1. This is heading 1
1.a. This is heading 2
1.b. Heading 2 again
1.b.i. This is heading 3
1.b.i.A. This is heading 4
2. Heading 1 again
2.a. Heading 2 yet again
Body text example.
2.a.i. Heading 3 again
2.a.ii. Heading 3 yet again
Much clearer. You can see straightaway that the body text is in section 2.a, even if section 2 started pages before. You don’t even need the indentation.
However, I don’t like the combination of numbers, letters and Roman numerals. Once you get to four levels, you have to start using upper and lower case to differentiate, and below that you have to use italics and other formatting. Nasty, unclear and confusing.
I much prefer to just stick with numbers, and to include all previous levels in the heading number, as follows:
1. This is heading 1
1.1. This is heading 2
1.2. Heading 2 again
1.2.1. This is heading 3
1.2.1.1. This is heading 4
2. Heading 1 again
2.1. Heading 2 yet again
Body text example.
2.1.1. Heading 3 again
2.1.2. Heading 3 yet again
Much nicer.
Now, there is an argument to be made for putting numbers in front of every paragraph, so that you can immediately refer to a clause in a document. Legal documents do this of course, but they also use weird-shaped paper, so we can safely ignore that industry. The numbers would increase greatly, and you’d need to make sure the Styles and Table of Contents played nicely together, but it would be very useful, especially in my field of Requirements Management, where each paragraph is a clause to be tracked and addressed.