Hi.
I am a web page.
I am written in "ISO HTML".
In 2025, most pages get written with this at the top:
<!DOCTYPE html>
Whereas I start with this:
<!DOCTYPE HTML PUBLIC "ISO/IEC 15445:2000//DTD HyperText Markup Language//EN">
DOCTYPE
stands for "Document Type Declaration." An SGML declaration defining
the format for what tags and attributes and in what order they can occur.
HTML stands for Hypertext Markup Language. Millions of people, perhaps billions,
read and use and write HTML every day.
PUBLIC I suppose means that this is a "public" standard.
I suppose as opposed to a "private" DOCTYPE. The person who wrote this page
created a modified DOCTYPE around the year 2000 for private use
so he could validate HTML with EMBED and NOBR tags. And to
validate pages with other non-standard Netscape Navigator and Internet Explorer code such as:
<BODY MARGINWIDTH="0" MARGINHEIGHT="0" TOPMARGIN="0" BOTTOMMARGIN="0" LEFTMARGIN="0" RIGHTMARGIN="0">
Meanwhile, I am a standards-based page.
I don't know anyone else using ISO HTML, but the excellent W3C Validator will still validate ISO HTML. It is a standard. I am a valid page. My code has validity.
Where was I?
Oh, I was explaining this:
<!DOCTYPE HTML PUBLIC "ISO/IEC 15445:2000//DTD HyperText Markup Language//EN">
ISO stands for the International Organization for Standardization.
IEC stands for the International Electrotechnical Commission.
15445 is the number assigned to this HTML standard.
15444 is the JPEG 2000 standard. 15398
regulates "the minimum requirements, proofs of suitability and auditing standards for manhole covers made of thermoplastics."
:2000 stands for the year 2000. There are no versions of ISO HTML after this one.
The world, it turned out, did not need ISO HTML enough to have it move forward in time. Or maybe it did, I merely am ignorant of why the world needed it.
The slashes // separate major parts of the document type.
There used to be so many doctypes. Go read this 17-year-old Stack Overflow question: What are the different doctypes in html and what do they mean?
Today, it's better. The HTML5 DOCTYPE is short enough to memorize.
<!DOCTYPE html>
DTD HyperText Markup Language is self-explanatory. "HyperText" is one word with a capital letter in the middle. It's a quixotic stylization.
Lastly, EN is English.
ISO HTML includes these tags:
MDN includes all these tags as known HTML tags in 2025. There are 3 tags in ISO HTML that are deprecated in HTML5. The rest are still perfectly valid, 25 years later.
Those still appear on the MDN website. It appears all the tags in ISO HTML still work pretty well. Despite 3 of the tags being "deprecated."
MDN includes this warning for those tags:
Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.
I suppose we all may cease to work at any time. For now, I am here, and I am valid.
This page was authored by hand in October 2025 by Joe Crawford for Weird Web October 2025. The prompt was "Deprecated."