process

So you wanna develop a new microformat?

Why?

There must be a problem to be solved. No problem, no microformat.

Once you've found your 'problem,' ask yourself: 'is there a simpler problem here?' If so, let's solve that problem first. We want to deal with the simplest problems first and only then build up to more complex problems.

Also, ask around on the web. Chances are that someone else has encountered the same problem as you. If you still believe that you have an unsolved problem, post something to the [microformats-discuss] mailing list or any other public channel (see mf.org/discuss/) We want to involve all interested parties in the discussion.

Document Current Behavior

Document current human behavior. Remember, we're paving the cowpaths- before you do that you have to find the cowpaths. Your documentation should be a collection of real world sites and pages which are publishing the kind of data you wish to structure with a microformat. From those pages and sites, you should extract markup examples and the schemas implied therein, and provide analyses of the same.

This collection of examples should be public, preferably on a wiki because there's no way you can do it by yourself (no matter how many of you there are). The reviews-formats page is a good example of research done before the creation of a microformat. Before developing hreview, the collaborators went out, documented current practices around reviews on web sites, and provided some analysis of the schemas implied therein.

It's quite possible during this step that you'll find someone else who has dealt with the problem you're addressing. Perhaps even solved it. Do your best to open a dialog with others who have encountered the same problem. We don't want to build walls between competing communities - we want people to work together to develop a good solution which will cover the majority of cases.

Propose a Microformat

Actually, DON'T!!!

There are other things to try before developing a microformat. First, ask yourself these questions:

1. Is there a standard element in XHTML that would work?
2. Is there a compound of XHTML elements that would work?
3. Ok, if the answer to the above two is 'no,' we can talk about a microformat.

For more details on semantic XHTML, examples of using XHTML elements, and constructing XHTML compounds, see The Elements of Meaningful XHTML.

First you should observe the microformats principles

After you understand the principes, ask yourself: "are there any well established, interoperably implemented standards we can look at which address this problem?" For example, hCard and hCalendar were built on top of the IETF standards for vCard and iCal, respectively, both of which are widely interoperably implemented. The developers of those standards had already spent many years in standards committees arguing about and developing the schemas. Better to leverage all the hard work that others have done before you, than to go off as a solo cowboy inventor, and waste time repeating all their mistakes. It's also much easier to start from a well established schema, and map into into XHTML than to develop a new schema.

Remember, microformats should be designed for humans first and machines second. Here are few questions that may help you decide if you really need a microformat for the problem you are trying to solve:

1. If I looked at this microformat in a browser that didn't support CSS or had CSS turned off, would it still be human readable?
2. Are this format's elements stylable with CSS?

If the proposed format doesn't pass these two things, it's not likely to gain much acceptance. Remember: humans first, machines second.

Iterate

After proposing a microformat, you'll likely get a lot of feedback from others' interested in microformats. The proposal needs to be iterated and adapted. Microformat development should be collaborative and communtiy based.

Here's an ASCII-art flow diagram:

DIAGRAM:
problem statement---->research/discussion---->proposal/draft---->standard
^________________V   ^___________________V   ^______________V

Note that each stage involves iteration. That iteration consists of discussion and feedback and may result in major changes. Do not be afraid to make major changes and please don't get too attached to any particular solutions.