You use the <h1> through <h6> elements to create headings in your documents. These are the familiar headings from HTML: <h1> creates the largest text and <h6> produces the smallest. These elements are supported in 1.0 Strict, 1.0 Transitional, 1.0 Frameset, and XHTML 1.1. Here are the possible attributes of these elements and which versions of XHTML support them:
align— Gives the alignment of text in the heading. The possible values are left (the default), center, right, and justify. (XHTML 1.0 Transitional, XHTML 1.0 Frameset.)
class— Gives the style class of the element. (XHTML 1.0 Strict, XHTML 1.0 Transitional, XHTML 1.0 Frameset, XHTML 1.1.)
dir— Sets the direction of text that doesn't have an inherent direction ...