The date:seconds function returns the number of seconds specified by the argument string. If no argument is given, then the current local date/time, as returned by date:date-time is used as a default argument.

The argument string may be in one of the following formats:

1. A right-truncated date/time string in one of the formats defined in [XML Schema Part 2: Datatypes]. In these cases, the difference between the date/time string and 1970-01-01T00:00:00Z is calculated as with date:difference and the result is converted to seconds with date:seconds.

   The legal formats are as follows:

   • xs:dateTime (CCYY-MM-DDThh:mm:ss)
   • xs:date (CCYY-MM-DD)
   • xs:gYearMonth (CCYY-MM)
   • xs:gYear (CCYY)

2. A duration specified in days, hours, minutes and seconds in the format defined for xs:duration in [3.2.6 duration] of [XML Schema Part 2: Datatypes]. The number of years and months in the duration string must both be equal to zero: either P0Y0M120D or P120D are permitted, but P3M is not.

   If the argument to date:seconds is defined as a duration, the number returned is the result of converting the duration to seconds by assuming that 1 day = 24 hours, 1 hour = 60 minutes and 1 minute = 60 seconds.

   The permitted duration format is basically PnDTnHnMnS, although implementers should consult [XML Schema Part 2: Datatypes] and [ISO 8601] for details.

If the argument is not in any of these formats, date:seconds returns NaN.