Before reading more about the specifics of Level Zero, you may wish to look at the project's Philosophy.
Coremob Level 0 is a de facto spec, aiming to describe the current state of the Mobile Web Platform. It is based off of market shares of the default browsers on deployed smartphone and tablet handsets. For the purpose of simplicity, this was roughly identified as the intersection in feature set of the Android 2.2 Froyo and iOS5 default browsers but with standard syntax.
Please note that the document linked above is a VERY EARLY DRAFT and needs to be read as such. If you are prone to outbursts of anger or ranting, read it some other day when it is more stable. If you wish to make useful, early contributions, they are very much welcome.
Research to identify the specs both these operating system implemented was carried out through tests, external sources of information like caniuse.com, feedback from developers, etc.
We're hoping that the more detailed tests developed for Ringmark will help us determine more precisely which specs belong in Coremob level 0. That is an ongoing process in the group.
We'll need to keep in mind that we want Level 0 to be a sound description of the current state of the world and Level 1 to be very focused on a small number of high-impact features. In other words, if the result of the tests show a great difference in support between Froyo (2.2) and Gingerbread (2.3), it's reasonable to lower the reach of level 0 in order to maintain Level 1 super focused.
- Analyze the output of Ringmark tests to more clearly understand the support for each spec on each platform.
- Adapt the specs depending on those results.