This is intro text; it should remain at page top.=0= This is an unorthodox h1 headed section. Normally we start headings with h2 instead because h1 is used for a page's name in MediaWiki and it is therefore illogical to use if for page section headings.
Second paragraph of section 0
Text of section 1
Text of section 1.1
Text of section 1.2
Second paragraph of section 1.2
Text of section 2
Text of section 2.1
Text of section 2.2
Text of too-low-level section 2.2.1.1
Text of section 2.3
Text of section 3
Text of section 4
Second paragraph of section 4