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Source for wiki TimeCowan version 15

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cowan

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TimeCowan

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== Calendar Time ==

`(current-posix-second)`

Returns a rational number representing the current second of the Posix epoch, which began on 00:00:00 on 1 January 1970, Coordinated Universal Time but excludes all leap seconds.  Implementations SHOULD return a value that:

 * Is as accurate as reasonably achievable.
 * Provides at least 1-second precision.
 * Provides a range of at least 2^31^ seconds before and after the epoch.

If the implementation cannot provide such a value, either temporarily or permanently, when `current-posix-seconds` is invoked, it MUST return `#f`.

== Elapsed Time ==

`(current-jiffy)`

Returns an exact integer representing the number of jiffies (arbitrary elapsed time units) since an arbitrary epoch, an implementation such as the time the program started running, the operating system was booted, or anything else.  Leap seconds are ''not'' excluded.  Implementations SHOULD return a value that:

 * Is as accurate as reasonably achievable.
 * Provides at least 1-second precision.
 * Provides a range of at least 2^31^ seconds before and after the epoch.

If the implementation cannot provide such a value, either temporarily or permanently, when `current-jiffy` is invoked, it MUST return `#f`.

`(jiffies-per-second)`

Returns an exact integer representing the number of jiffies per SI second.  This value is an implementation-specified constant.

== Date and Time Arithmetic (WG2) ==

See TimeAdvancedCowan.

== Time Durations and Periods (WG2) ==

See TimePeriodsCowan.

== Time formatting (WG2) ==

See TimeFormattingCowan.

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2010-12-11 07:10:54