DOCBOOK-APPS: Inclusion of random section in the TOC

[Adrian Ionita <silviu dot ionita at probass dot ro>]

It is possible to specify with an attribute (or something else) of the
<section> element if that section is or isn't included in the TOC?

I don't want an entire level to be included or not in the TOC (with a
global parameter that specify the depth TOC of sections
'toc.section.depth')

For example I have the next structure:
	Chapter 1
		Section 1.1
			 Section 1.1.1
		Section 1.2
			Section 1.2.1
	Chapter 2
		Section 2.1
			Section 2.1.1
		Section 2.2
		Section 2.3
			Section 2.3.1
				Section 2.3.1.1
				Section 2.3.1.2
				Section 2.3.1.3
			Section 2.3.2

And I want that my TOC to look in this way:
	Chapter 1
		Section 1.1
		Section 1.2
			Section 1.2.1
	Chapter 2
		Section 2.1
		Section 2.2
		Section 2.3
			Section 2.3.1
				Section 2.3.1.1
				Section 2.3.1.2
			Section 2.3.2

I omitted the following sections:
- Section 1.1.1
- Section 2.1.1
	- Section 2.3.1.3

It's possible to make this without manual creation of TOC?

Note: I use 'sgmltools' to parse the sources.