The use of open data standards by content producers and consumers is a good thing, but it’s hard for someone outside a field of endeavor to understand what those standards are and exactly how important they are. (For instance, it doesn’t take a lot of time working with online calendars to grasp that iCalendar is an important standard, but it did take me some study to grasp how central it really is.) Hence, it is helpful if for every subject you could find a simple, clear articulation of the standards for a given field. In the absence of a clear consensus about what the relevant standards are, a trustworthy and ­clear-­headed outline of the main contenders and the perceived strengths and weaknesses would be really helpful to an outsider or newbie.

The Cover Pages (http://xml.coverpages.org/) hosted by OASIS is the closest thing to such a resource that I’ve seen:

Complementing a wide use of open standards is a concerted effort to generate API kits that comprehensively and accurately interpret these standards. For example, as you’ll see in Chapter 15 in the discussion iCalendar, it’s hard to tell how good any given API kit is at interpreting and creating that data format.

Moreover, the presence of good validators and schemas for any data formats would be extremely helpful to mashup developers. For example, the early days of working with KML were hard because there was so much trial and error with writing something and then feeding it to Google Earth to see whether it would work. With good validators in place, data producers can debug their data without less experimentation. Some examples of useful validators are as follows: