The WWP does not make any specific encoding of times or references to times under ordinary circumstances. We only encode references to times which are used to indicate the structure of a section (for instance, entries in a diary). For these cases, we will use <time>.
In the cases where we use this element, we encode a regularized value in the value= attribute, using ISO 8601:1988 (E) extended formats, where one is applicable, and the basic format where an extended format is not applicable. Times are expressed with a 24-hour clock. Hours are expressed as a two-digit integer ranging from 00 to 23; minutes and seconds are two-digits each, ranging from 00 to 59. (The leading zeroes are required by 8601 (section 5.3.1); the colons are required by WWP, because we use the extended format whenever possible.) These three components are separated from each other by colons.
If you know the whole time (precise to the second, very unlikely in our period): 03:25:30
This is called the complete representation, extended format (section 220.127.116.11).
If you don’t have the seconds (precise to the minute, probably the most common case, e.g. “twenty-five past three”): 03:25
If you have only the hour (e.g. “the baby woke up in the middle of the night -- around three”): 03
Note that midnight is the first second (or minute, depending on your precision) of the day. Thus the second following 1997-09-19T23:59:59 is 1997-09-20T00:00:00.
Combined date and time
A combined date and time can be expressed by juxtaposing the respective values for the date and time, and separating them with a “T” (no spaces). So Isabelle was born 1996-09-24T03:25. A range can be expressed using both dates and times, too:
During the period 1997-07-27T09:30/1997-08-01T23:00 I got 21 hours of sleep.
By default, a value which combines date and time should be encoded with <date>. However, in a rare context (such as a list of times) where almost all instances are encoded with <time> but one instance provides a date as well, for consistency <time> should be used.