Simple and complex lists

The html4css1.HTMLTranslator docstring says:

This HTML writer has been optimized to produce visually compact lists (less vertical whitespace). HTML's mixed content models allow list items to contain "<li><p>body elements</p></li>" or "<li>just text</li>" or even "<li>text<p>and body elements</p>combined</li>", each with different effects. It would be best to stick with strict body elements in list items, but they affect vertical spacing in browsers (although they really shouldn't).

Here is an outline of the optimization:

• Check for and omit <p> tags in "simple" lists: list items contain either a single paragraph, a nested simple list, or a paragraph followed by a nested simple list. This means that this list can be compact:

  • Item 1.

  • Item 2.

  But this list cannot be compact:

  • Item 1.

    This second paragraph forces space between list items.

  • Item 2.

• In non-list contexts, omit <p> tags on a paragraph if that paragraph is the only child of its parent (footnotes & citations are allowed a label first).

• Regardless of the above, in definitions, table cells, field bodies, option descriptions, and list items, mark the first child with 'class="first"' and the last child with 'class="last"'. The stylesheet sets the margins (top & bottom respectively) to 0 for these elements.

The no_compact_lists setting (--no-compact-lists command-line option) disables list whitespace optimization.

In html4_strict, the algorithm to determine if a list is "simple" enough to be compacted includes field lists (in addition to ordered lists and unordered lists).