I am reading and taking notes on the HTML specifications for 100 days as part of #The100DayProject. Read the initial intent/backstory. I am a Microsoft employee but all opinions, comments, etc on this site are my own. I do not speak on behalf of my employer, and thus no comments should be taken as representative of Microsoft's official opinion of the spec. Subsections not listed below were read without comment.
Currently reading in 2.4 Common microsyntaxes
Like the microformats yesterday, a "time" still doesn't contain a time zone, just hour, minute, second, and fraction of a second.
Hours are given in military time (0 <= hour <= 23). By the way, I always find it interesting when I come across an American who has their phone clock set to the 24-hour system.
126.96.36.199 Floating dates and times
A "floating date and time" contains both the date and time information.
When it becomes a "valid normalized floating date and time string", it does not contain a U+0020 SPACE character (which a "valid floating date and time string" can have), and the time is "expressed as the shortest possible string for the given time (e.g. omitting the seconds component entirely if the given time is zero seconds past the minute)".
188.8.131.52 Time zones
Re, time zone offsets: "This format allows for time-zone offsets from -23:59 to +23:59. In practice, however, right now the range of offsets of actual time zones is -12:00 to +14:00, and the minutes component of offsets of actual time zones is always either 00, 30, or 45. There is no guarantee that this will remain so forever, however; time zones are changed by countries at will and do not follow a standard."