blog atom可的时间格式

有用W3C Date-Time : YYYY-MM-DDThh:mm:ss.sTZD

Formats

Different standards may need different levels of granularity in the date
and
time, so this profile defines six levels.
Standards that reference this profile should specify one or more of these
granularities.
If a given standard allows more than one granularity, it should specify
the meaning of the dates and times with reduced precision,
for example, the result of comparing two dates with different precisions.

The formats are as follows.
Exactly the components shown here must be present, with exactly this
punctuation.
Note that the "T" appears literally in
the string, to indicate the beginning of the time element, as specified in
ISO 8601.

   Year:
      YYYY (eg 1997)
   Year and month:
      YYYY-MM (eg 1997-07)
   Complete date:
      YYYY-MM-DD (eg 1997-07-16)
   Complete date plus hours and minutes:
      YYYY-MM-DDThh:mmTZD (eg 1997-07-16T19:20+01:00)
   Complete date plus hours, minutes and seconds:
      YYYY-MM-DDThh:mm:ssTZD (eg 1997-07-16T19:20:30+01:00)
   Complete date plus hours, minutes, seconds and a decimal fraction of a
second
      YYYY-MM-DDThh:mm:ss.sTZD (eg 1997-07-16T19:20:30.45+01:00)

where:

     YYYY = four-digit year
     MM   = two-digit month (01=January, etc.)
     DD   = two-digit day of month (01 through 31)
     hh   = two digits of hour (00 through 23) (am/pm NOT allowed)
     mm   = two digits of minute (00 through 59)
     ss   = two digits of second (00 through 59)
     s    = one or more digits representing a decimal fraction of a second
     TZD  = time zone designator (Z or +hh:mm or -hh:mm)

This profile does not specify how many digits may be used to represent
the decimal fraction of a second. An adopting standard that permits
fractions of a second must specify
both the minimum number of digits (a number greater than or equal to
one) and the maximum number of digits (the maximum may be stated to be
"unlimited").

This profile defines two ways of handling time zone offsets:

1. Times are expressed in UTC (Coordinated Universal Time), with a
   special UTC designator ("Z").
   
2. Times are expressed in local time, together with a time zone offset
   in hours and minutes. A time zone offset of "+hh:mm" indicates that
   the date/time uses a local time zone which is "hh" hours and "mm"
   minutes ahead of UTC. A time zone offset of "-hh:mm" indicates that
   the date/time uses a local time zone which is "hh" hours and "mm"
   minutes behind UTC.
   

A standard referencing this profile should permit one or both of these
ways of handling time zone offsets.

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