Why won't elements validate in HTML 4.01?</a></h1> </div> <div class="grid fw-wrap pb8 mb16 bb bc-black-075"> <div class="grid--cell ws-nowrap mr16 mb8" title="2016-01-12 19:07:53Z"> <span class="fc-light mr2">Asked</span> <time itemprop="dateCreated" datetime="2011-02-02T10:51:31.357" class="fromnow">Feb 02 '11 at 10:51</time> </div> <div class="grid--cell ws-nowrap mr16 mb8"> <span class="fc-light mr2">Active</span> <time class="fromnow" title="2011-02-02T11:31:20.143" datetime="2011-02-02T11:31:20.143">Feb 02 '11 at 11:31</a> </div> <div class="grid--cell ws-nowrap mb8" title="Viewed 8,094 times"> <span class="fc-light mr2">Viewed</span> 8,094 times </div> </div> <div id="mainbar" role="main" aria-label="questions and answers"> <div id="question" class="question" data-questionid="4873502" data-ownerid="363356" data-score="4"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container grid jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="4873502"> <button class="js-vote-up-btn grid--cell s-btn s-btnunset c-pointer"><svg aria-hidden="true" class="m0 svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 26h32L18 10 2 26z"></path></svg></button> <div class="js-vote-count grid--cell fc-black-500 fs-title grid fd-column ai-center" itemprop="upvoteCount" data-value="4">4</div> <button class="js-bookmark-btn s-btn s-btnunset c-pointer py4"> <svg aria-hidden="true" class="svg-icon iconBookmark" width="18" height="18" viewBox="0 0 18 18"><path d="M6 1a2 2 0 00-2 2v14l5-4 5 4V3a2 2 0 00-2-2H6zm3.9 3.83h2.9l-2.35 1.7.9 2.77L9 7.59l-2.35 1.7.9-2.76-2.35-1.7h2.9L9 2.06l.9 2.77z"></path></svg> <div class="js-bookmark-count mt4" data-value=""></div> </button> </div> </div> <div class="postcell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"><p>I was just checking to see if it was valid to put an <code><iframe></code> element inside a <code><noscript></code> element as a fall back for displaying dynamic content. It validated fine with the HTML 5 doctype, but for HTML 4.01, I get the following error:</p> <blockquote> <p><strong>Line 9, Column 35: element "IFRAME" undefined</strong><br/> <iframe name="test" src="test.htm"></iframe></p> <p>You have used the element named above in your document, but the document type you are using does not define an element of that name. This error is often caused by:</p> <ul> <li>incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Frameset" document type to get the "" element),</li> <li>by using vendor proprietary extensions such as "" or "" (this is usually fixed by using CSS to achieve the desired effect instead).</li> <li>by using upper-case tags in XHTML (in XHTML attributes and elements must be all lower-case).</li> </ul> </blockquote> <p>This is what I whittled the HTML down to:</p> <pre><code><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <title>I AM YOUR DOCUMENT TITLE REPLACE ME</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> <div> <iframe name="test" src="test.htm"></iframe> </div> </body> </html> </code></pre> <p>The <code><iframe></code> element is defined in the HTML 4.01 specification at the following URL: <a class="external-link" href="http://www.w3.org/TR/html401/present/frames.html#h-16.5" rel="nofollow noreferrer">http://www.w3.org/TR/html401/present/frames.html#h-16.5</a>.</p> <p>It passes with a transitional doctype, so I guess my question is "Why is it disallowed in a strict doctype, even though it's defined in the specification?".</p></div> <div class="mt24 mb12"> <div class="post-taglist grid gs4 gsy fd-column"> <div class="grid ps-relative"> <a href="../../questions/tagged/html" class="post-tag js-gps-track" title="show questions tagged 'html'" rel="tag">html</a> <a href="../../questions/tagged/iframe" class="post-tag js-gps-track" title="show questions tagged 'iframe'" rel="tag">iframe</a> <a href="../../questions/tagged/w3c-validation" class="post-tag js-gps-track" title="show questions tagged 'w3c-validation'" rel="tag">w3c-validation</a> <a href="../../questions/tagged/html4" class="post-tag js-gps-track" title="show questions tagged 'html4'" rel="tag">html4</a> </div> </div> </div> <div class="mb0"> <div class="mt16 grid gs8 gsy fw-wrap jc-end ai-start pt4 mb16"> <div class="grid--cell mr16 fl1 w96"></div> <div class="post-signature grid--cell"> <div class="s-user-card s-user-card"> <time class="s-user-card--time" datetime="edited Jun 20 '20 at 09:12">edited Jun 20 '20 at 09:12</time> <a href="../../users/-1/community" class="s-avatar s-avatar32 s-user-card--avatar"> <img class="s-avatar--image" src="../../users/profiles/-1.webp" data-jdenticon-width="32" data-jdenticon-height="32" data-jdenticon-value="Community" /> </a> <div class="s-user-card--info"> <a href="../../users/-1/community" class="s-user-card--link">Community</a> <ul class="s-user-card--awards"> <li class="s-user-card--rep" title="reputation score">1</li> <li class="s-award-bling s-award-blingsilver" title="1 silver badges">1</li> </ul> </div> </div> </div> <div class="post-signature owner grid--cell"> <div class="s-user-card s-user-card"> <time class="s-user-card--time" datetime="asked Feb 02 '11 at 10:51">asked Feb 02 '11 at 10:51</time> <a href="../../users/363356/jujurawrs" class="s-avatar s-avatar32 s-user-card--avatar"> <img class="s-avatar--image" src="../../users/profiles/363356.webp" data-jdenticon-width="32" data-jdenticon-height="32" data-jdenticon-value="jujurawrs" /> </a> <div class="s-user-card--info"> <a href="../../users/363356/jujurawrs" class="s-user-card--link">jujurawrs</a> <ul class="s-user-card--awards"> <li class="s-user-card--rep" title="reputation score">43</li> <li class="s-award-bling s-award-blingsilver" title="1 silver badges">1</li> <li class="s-award-bling s-award-bling__bronze" title="5 bronze badges">5</li> </ul> </div> </div> </div> </div> </div> </div> <div class="post-layout--right js-post-comments-component"> <div id="comments-4873502" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="4873502" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-5418313" class="comment js-comment " data-comment-id="5418313" data-comment-owner-id="249976" data-comment-score="4"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="warm">4</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <a name="comment5418313_4873502"></a> <div class="comment-body js-comment-edit-hide"> <span class="comment-copy">Possibly it's not valid in the strict DTD. Can you move to Transitional?</span> – <a href="../../users/249976/craig" title="1,277 reputation" class="comment-user ">Craig</a> <span class="comment-date" dir="ltr"><a class="comment-link" href="../../questions/4873502/why-won-t-iframe-elements-validate-in-html-4-01#comment5418313_4873502"><span title="2011-02-02T10:55:20.733 License: CC BY-SA 2.5" class="relativetime-clean">Feb 02 '11 at 10:55</span></a></span> </div> </div> </li> <li id="comment-5418370" class="comment js-comment " data-comment-id="5418370" data-comment-owner-id="575766" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <a name="comment5418370_4873502"></a> <div class="comment-body js-comment-edit-hide"> <span class="comment-copy">@Craig: According to W3Schools it's ok, but that's the first thing I'd try too.</span> – <a href="../../users/575766/michael" title="7,348 reputation" class="comment-user ">Michael</a> <span class="comment-date" dir="ltr"><a class="comment-link" href="../../questions/4873502/why-won-t-iframe-elements-validate-in-html-4-01#comment5418370_4873502"><span title="2011-02-02T11:00:57.867 License: CC BY-SA 2.5" class="relativetime-clean">Feb 02 '11 at 11:00</span></a></span> </div> </div> </li> <li id="comment-5418503" class="comment js-comment " data-comment-id="5418503" data-comment-owner-id="363356" data-comment-score="2"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="warm">2</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <a name="comment5418503_4873502"></a> <div class="comment-body js-comment-edit-hide"> <span class="comment-copy">@Craig: you're right, it passes with transitional DTD - so why is it defined but not allowed? @Mikaveli: I wouldn't rely on the accuracy of W3Schools pages anyway.</span> – <a href="../../users/363356/jujurawrs" title="43 reputation" class="comment-user owner">jujurawrs</a> <span class="comment-date" dir="ltr"><a class="comment-link" href="../../questions/4873502/why-won-t-iframe-elements-validate-in-html-4-01#comment5418503_4873502"><span title="2011-02-02T11:11:47.750 License: CC BY-SA 2.5" class="relativetime-clean">Feb 02 '11 at 11:11</span></a></span> </div> </div> </li> </ul> </div> </div> </div> </div> <div id="answers"> <a name="tab-top"></a> <div id="answers-header"> <div class="answers-subheader grid ai-center mb8"> <div class="grid--cell fl1"> <h2 class="mb0" data-answercount="9">2 Answers<span style="display:none;" itemprop="answerCount">2</span></h2> </div> </div> </div> <a name="4873850"></a> <div id="answer-4873850" class="answer accepted-answer" data-answerid="4873850" data-ownerid="19068" data-score="5" itemprop="acceptedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container grid jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="4873850"> <button class="js-vote-up-btn grid--cell s-btn s-btnunset c-pointer"><svg aria-hidden="true" class="m0 svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 26h32L18 10 2 26z"></path></svg></button> <div class="js-vote-count grid--cell fc-black-500 fs-title grid fd-column ai-center" itemprop="upvoteCount" data-value="5">5</div> <div class="js-accepted-answer-indicator grid--cell fc-green-500 py6 mtn8"><div class="ta-center"><svg aria-hidden="true" class="svg-icon iconCheckmarkLg" width="36" height="36" viewBox="0 0 36 36"><path d="m6 14 8 8L30 6v8L14 30l-8-8v-8z"></path></svg></div></div> </div> </div> <div class="postcell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"><blockquote> <p>"Why is it disallowed in a strict doctype, even though it's defined in the specification?</p> </blockquote> <p>Lots of things are defined in the specification but not allowed in Strict. <code><font></code> springs to mind. These are the things that the developers of the specification considered in need of documenting, were in use in browsers in the day, but which should be transitioned away from.</p> <p>I can think of two reasons why they might have thought that:</p> <ul> <li>"<a href="../../questions/362730/are-iframes-considered-bad-practice">Why do iframes suck?</a>". </li> <li><code><iframe></code> does (in theory) little that can't be achieved with <code><object></code></li> </ul></div> <div class="mb0"> <div class="mt16 grid gs8 gsy fw-wrap jc-end ai-start pt4 mb16"> <div class="grid--cell mr16 fl1 w96"></div> <div class="post-signature grid--cell"> <div class="s-user-card s-user-card"> <time class="s-user-card--time" datetime="edited May 23 '17 at 09:58">edited May 23 '17 at 09:58</time> <a href="../../users/-1/community" class="s-avatar s-avatar32 s-user-card--avatar"> <img class="s-avatar--image" src="../../users/profiles/-1.webp" data-jdenticon-width="32" data-jdenticon-height="32" data-jdenticon-value="Community" /> </a> <div class="s-user-card--info"> <a href="../../users/-1/community" class="s-user-card--link">Community</a> <ul class="s-user-card--awards"> <li class="s-user-card--rep" title="reputation score">1</li> <li class="s-award-bling s-award-blingsilver" title="1 silver badges">1</li> </ul> </div> </div> </div> <div class="post-signature grid--cell"> <div class="s-user-card s-user-card"> <time class="s-user-card--time" datetime="answered Feb 02 '11 at 11:23">answered Feb 02 '11 at 11:23</time> <a href="../../users/19068/quentin" class="s-avatar s-avatar32 s-user-card--avatar"> <img class="s-avatar--image" src="../../users/profiles/19068.webp" data-jdenticon-width="32" data-jdenticon-height="32" data-jdenticon-value="Quentin" /> </a> <div class="s-user-card--info"> <a href="../../users/19068/quentin" class="s-user-card--link">Quentin</a> <ul class="s-user-card--awards"> <li class="s-user-card--rep" title="reputation score">914,110</li> <li class="s-award-bling s-award-blinggold" title="126 gold badges">126</li> <li class="s-award-bling s-award-blingsilver" title="1,211 silver badges">1,211</li> <li class="s-award-bling s-award-bling__bronze" title="1,335 bronze badges">1,335</li> </ul> </div> </div> </div> </div> </div> </div> <div class="post-layout--right js-post-comments-component"> <div id="comments-4873850" class="comments js-comments-container bt bc-black-075 mt12 " data-post-id="4873850" data-min-length="15"> <ul class="comments-list js-comments-list" data-remaining-comments-count="0" data-canpost="false" data-cansee="true" data-comments-unavailable="false" data-addlink-disabled="true"> <li id="comment-5418741" class="comment js-comment " data-comment-id="5418741" data-comment-owner-id="363356" data-comment-score="1"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> <span title="number of 'useful comment' votes received" class="warm">1</span> </div> </div> <div class="comment-text js-comment-text-and-form"> <a name="comment5418741_4873850"></a> <div class="comment-body js-comment-edit-hide"> <span class="comment-copy">Do you think it's acceptable to use an iframe to allow the server to display content where JavaScript is disabled? I'm accessing a web service using JavaScript to display some of the page's content, but I would like to fall back to an iframe where the server can make the request if JS isn't available.</span> – <a href="../../users/363356/jujurawrs" title="43 reputation" class="comment-user owner">jujurawrs</a> <span class="comment-date" dir="ltr"><a class="comment-link" href="../../questions/4873502/why-won-t-iframe-elements-validate-in-html-4-01#comment5418741_4873850"><span title="2011-02-02T11:30:40.323 License: CC BY-SA 2.5" class="relativetime-clean">Feb 02 '11 at 11:30</span></a></span> </div> </div> </li> <li id="comment-5418767" class="comment js-comment " data-comment-id="5418767" data-comment-owner-id="19068" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <a name="comment5418767_4873850"></a> <div class="comment-body js-comment-edit-hide"> <span class="comment-copy">@jujurawrs — that's a rather subjective and argumentative question, so I'm hesitant to discuss it here.</span> – <a href="../../users/19068/quentin" title="914,110 reputation" class="comment-user ">Quentin</a> <span class="comment-date" dir="ltr"><a class="comment-link" href="../../questions/4873502/why-won-t-iframe-elements-validate-in-html-4-01#comment5418767_4873850"><span title="2011-02-02T11:32:42.733 License: CC BY-SA 2.5" class="relativetime-clean">Feb 02 '11 at 11:32</span></a></span> </div> </div> </li> <li id="comment-5418816" class="comment js-comment " data-comment-id="5418816" data-comment-owner-id="363356" data-comment-score="0"> <div class="js-comment-actions comment-actions"> <div class="comment-score js-comment-edit-hide"> </div> </div> <div class="comment-text js-comment-text-and-form"> <a name="comment5418816_4873850"></a> <div class="comment-body js-comment-edit-hide"> <span class="comment-copy">How very diplomatic of you. Thanks for your time :-)</span> – <a href="../../users/363356/jujurawrs" title="43 reputation" class="comment-user owner">jujurawrs</a> <span class="comment-date" dir="ltr"><a class="comment-link" href="../../questions/4873502/why-won-t-iframe-elements-validate-in-html-4-01#comment5418816_4873850"><span title="2011-02-02T11:37:45.953 License: CC BY-SA 2.5" class="relativetime-clean">Feb 02 '11 at 11:37</span></a></span> </div> </div> </li> </ul> </div> </div> </div> </div> <a name="4873854"></a> <div id="answer-4873854" class="answer " data-answerid="4873854" data-ownerid="408106" data-score="3" itemprop="suggestedAnswer" itemscope="" itemtype="https://schema.org/Answer"> <div class="post-layout"> <div class="votecell post-layout--left"> <div class="js-voting-container grid jc-center fd-column ai-stretch gs4 fc-black-200" data-post-id="4873854"> <button class="js-vote-up-btn grid--cell s-btn s-btnunset c-pointer"><svg aria-hidden="true" class="m0 svg-icon iconArrowUpLg" width="36" height="36" viewBox="0 0 36 36"><path d="M2 26h32L18 10 2 26z"></path></svg></button> <div class="js-vote-count grid--cell fc-black-500 fs-title grid fd-column ai-center" itemprop="upvoteCount" data-value="3">3</div> </div> </div> <div class="postcell post-layout--right"> <div class="s-prose js-post-body" itemprop="text"><p>iframe isn't included in html strict. For validation, try using the object element instead.</p> <pre><code><object data="test.html" type="text/html"></object> </code></pre> <p>You should also add width and height attributes to the object element. Note, unlike iframes objects cannot be a target for any page links.</p> <p>Unless for some reason you specifically need html4 strict validation, it's better to use the html5 doctype.</p></div> <div class="mb0"> <div class="mt16 grid gs8 gsy fw-wrap jc-end ai-start pt4 mb16"> <div class="grid--cell mr16 fl1 w96"></div> <div class="post-signature grid--cell"> <div class="s-user-card s-user-card"> <time class="s-user-card--time" datetime="answered Feb 02 '11 at 11:23">answered Feb 02 '11 at 11:23</time> <a href="../../users/408106/leebriggs" class="s-avatar s-avatar32 s-user-card--avatar"> <img class="s-avatar--image" src="../../users/profiles/408106.webp" data-jdenticon-width="32" data-jdenticon-height="32" data-jdenticon-value="leebriggs" /> </a> <div class="s-user-card--info"> <a href="../../users/408106/leebriggs" class="s-user-card--link">leebriggs</a> <ul class="s-user-card--awards"> <li class="s-user-card--rep" title="reputation score">3,187</li> <li class="s-award-bling s-award-blinggold" title="1 gold badge">1</li> <li class="s-award-bling s-award-blingsilver" title="20 silver badge">20</li> <li class="s-award-bling s-award-bling__bronze" title="17 bronze badge">17</li> </ul> </div> </div> </div> </div> </div> </div> <div class="post-layout--right js-post-comments-component"> </div> </div> </div> </div> </div> <div id="sidebar" class="show-votes" role="complementary" aria-label="sidebar"> <div class="module sidebar-linked"> <h4 id="h-linked">Linked</h4> <div class="linked"> <div class="spacer"> <a title="Vote score (upvotes - downvotes)"><div class="answer-votes default">-1</div></a> <a href="../../questions/35160629/w3c-validation-errors-with-embedded-google-map" class="question-hyperlink">W3C validation errors with embedded google map</a> </div> </div> </div> </div> </div> </div> <script src="../../static/js/stack-icons.js"></script> <script src="../../static/js/fromnow.js"></script> </body> </html>