Frames shall be titled with text that facilitates frame identification and navigation.

General comments

"Frames" let a web developer divide the browser's screen into several different areas, each displaying a different web page.  Each of the different frames can act independently of other frames or can be designed to control the contents of other frames.  For example, a narrow frame down the left side could be used for navigation links, with a large right-hand frame for the content of the selected link, and a third frame across the top for the title of the Web site.  Every time the user chooses a different link, the contents of the right-hand frame are refreshed with new information.  The user can move down the list of possible destinations and choose different options without disturbing the list of navigation links.

If frames are not implemented properly, those who use screen readers may have difficulty determining from which frame the screen reader is reading.  However, properly labelled frames may actually improve accessibility by creating an easy-to-reach area which is specifically designed for navigating a website and which is unaffected by visiting different areas of the website.

Making Frames Accessible.  Both the <FRAMESET> and <FRAME> tags support an attribute called "title" that can be used to describe the contents of the frameset or frame.  Titles such as "Left," "Right," or "Top" provide little useful information as to what is contained in the frame.  Better would be titles like "Site Navigation," "Main Content" and "DOC Operations Center."

Inline Frames.  A new but closely related way to offer greater flexibility in web page design is with inline frame technology, which enables web designers to place frames of any size at any location on the screen.  Creating an inline frame involves nothing more than including an <IFRAME> tag within the content of a regular web page.  To ensure that web pages using frames -- conventional or inline -- are accessible to people with disabilities, designers should provide a meaningful title for each frame.

The <NOFRAMES> tag.  This tag may be used to provide an alternative for those using browsers that don't support frames.  If you do use frames, and you compose your pages with some popular Web design tools, those tools may automatically insert a NOFRAMES element that displays the following text message to anyone using a browser that doesn't support frames:

"This web page uses frames,
but your browser doesn't support them."

The above is almost worse than no explanation.

DOJ Appendix on Making Frames Accessible

HTML Techniques for WCAG 1.0/Frames