Links and Webs - HTML and XHTML: The Definitive Guide - page 327

The HReflang attribute may be specified only when the href attribute is
used. Like the lang attribute, its value is an International Organization
for Standardization (ISO) standard two-character language code. Unlike
the lang attribute, the HReflang attribute does not address the language
used by the contents of the tag. Instead, it specifies the language used
in the document referenced by the href attribute. [ The lang attribute,
3.6.1.2 ]
The type attribute specifies the content type of the resource referenced
by the <a> tag. Its value is any Multipurpose Internet Mail Extension
(MIME) encoding type. For example, you might inform the browser that
you are linking to a plain ASCII document with:
<a href="readme.txt" type="text/plain">
The browser might use this information when displaying the referenced
document, or might even present the link differently based upon the
content type.
6.3.1.11. The coords and shape attributes
Two more attributes are defined in the HTML and XHTML standards for
the <a> tag but are not supported by the currently popular browsers.
Like the attributes of the same names for the <area> tag, the coords
and shape attributes define a region of influence for the <a> tag. You
should use these attributes with the <a> tag only when that tag is part of
the content of a <map> tag, as described later in this chapter. [ <map>,
6.5.3 ] [ The coords attribute, 6.5.4.2 ] [ The shape attribute, 6.5.4.7 ]
6.3.1.12. The accesskey and tabindex attributes
Traditionally, users of graphical browsers select and execute a hyperlink
by pointing and clicking the mouse device on the region of the browser
display defined by the anchor. What is less well known is that you may