A frame document contains no displayable content, except perhaps a
message for nonframes-enabled browsers. Instead, <frame> tags inside one or more <frameset> tags (which encapsulate the
contents of a frame document) provide URL references to the
individual documents that occupy each frame. [<noframes>, 11.5]
The <frame> tag
appears only within a <frameset>. Use it to set, via its
associated src attribute, the URL
of the document content that initially gets displayed inside the
respective frame.
Browsers place the frame contents into the frameset column by
column, from left to right, and then row by row, from top to bottom.
Accordingly, the sequence and number of <frame> tags inside the <frameset> tag are important.
The browser displays empty frames for <frame> tags that do not have src attributes. It also displays empty
frames if the <frameset> tag
calls for more frames than the corresponding <frame> tags define—if your frame
document calls for three columns and you provide only two frames, for
example. Orphan frames remain empty, and you cannot put content into
them later, even if they have a target name or id for display redirection. [The name and id attributes,
11.4.1.2]
The value of the src attribute for the <frame> tag is the URL of the document that is to be
displayed in the frame. There is no other way to provide content for
a frame. You shouldn't, for instance, include any <body> content within the frame
document; the browser ignores the frame tags and displays just the
contents of a <body> tag if
it comes first, or vice versa.
The document referenced by the src attribute may be any valid document or
any displayable object, including images and multimedia. In
particular, the referenced document may itself be composed of one or
more frames. The frames are displayed within the referencing
frame, providing yet another way of achieving complex layouts using
nested frames.
Because the source may be a complete document, all the
features of HTML/XHTML apply within a frame, including backgrounds
and colors, tables, fonts, and the like. Unfortunately, this also
means that multiple frames in a single browser window may conflict
with each other. Specifically, if each nested frame document (not a
regular HTML or XHTML document) has a different <title> tag, the title of the
overall browser window is the title of the most recently loaded
frame document. The easiest way to avoid this problem is to ensure
that all related frame documents use the same title.
The optional name attribute
for the <frame> tag labels
that frame for later reference by a target attribute for the anchor (<a>) tag and the <form> tag. This way, you can alter
the contents of a frame using a hyperlink in another frame.
Otherwise, like normal browser windows, linked documents replace the
contents of the source frame. We discuss names and targets at
greater length later in this chapter. [The target Attribute for the
<a> Tag, 11.7.1]
Similarly, the id attribute
uniquely identifies a frame, but the browsers do not support its use
for target redirection, even though they do support id's use as a hyperlink target in many
other HTML and XHTML tags.
The value of the name or
id attribute is a text string
enclosed in quotation marks.
Even though you may explicitly set frame dimensions with
attributes in the <frameset> tag, users can manually
alter the size of a column or row of frames. To suppress this
behavior, add the noresize
attribute to the frame tags in the row or column whose relative
dimensions you do not want users fiddling with. For example, for a
two-by-two frame document, a noresize attribute in any one of the four
associated frame tags effectively freezes the relative proportions
of all the frames.
The noresize attribute is
especially useful for frames that contain fixed images serving as
advertisements, a button bar, or a logo. By fixing the size of the
frame to contain just the image and setting the noresize attribute, you guarantee that the
image is displayed in the intended manner and that the remainder of
the browser window is always given over to the other frames in the
document.
The browser displays vertical and horizontal scroll
bars with frames whose contents are larger than the allotted window
space. If there is sufficient room for the content, the scroll bars
disappear. The scrolling
attribute for the <frame>
tag gives you explicit control over whether the
scroll bars appear or disappear.
With scrolling="yes", all
the popular browsers except Netscape add scroll bars to the
designated frame even if there is nothing to scroll. If you set the
scrolling attribute value to
no, scroll bars are never added
to the frame, even if the frame contents are larger than the frame
itself. The value auto, the
default, works as though you didn't include the scrolling attribute in the tag.
The browser normally places a small amount of space between
the edge of a frame and its contents. You can change those margins
with the marginheight and
marginwidth attributes, each
including a value for the exact number of pixels to place around the
frame's contents.
You cannot make a margin less than 1 pixel or make it so large that there is no room for the frame's contents. That's because, like most other HTML attributes, these advise; they do not dictate to the browser. If your desired margin values cannot be accommodated, the browser ignores them and renders the frame as best it can.
With some earlier versions of Internet Explorer, you could add
and remove borders from a single frame with the frameborder attribute. Values of yes or 1 and no or 0
respectively enable or disable borders for the frame and override
the value of the frameborder
attribute for any frameset containing the frame. Don't use
it.
With all the popular browsers except Opera, you also can
change the color of the individual frame's borders with the bordercolor attribute. Use a color name or
hexadecimal triple as its value. If two adjacent frames have
different bordercolor attributes,
the resulting border color is undefined. You can find a complete
list of color names and values in Appendix G.
Like most other standard tags, you can provide a title
for a frame with the title
attribute. The value of the attribute is a quote-enclosed string
that describes the contents of the frame. Browsers might display the
title, for instance, when the mouse passes over the frame.
If the title attribute
isn't quite enough for you, you can use the longdesc attribute. Its value is the URL
of a document that describes the frame. Presumably, this long
description might be in some alternative media, suitable for use by
a nonvisual browser.