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A DateTime value shall be encoded as a 64-bit signed integer (see Clause 5.2.2.2) which represents the number of 100 nanosecond intervals since January 1, 1601 (UTC).

Not all DevelopmentPlatforms will be able to represent the full range of dates and times that can be represented with this DataEncoding. For example, the UNIX time_t structure only has a 1 second resolution and cannot represent dates prior to 1970. For this reason, a number of rules shall be applied when dealing with date/time values that exceed the dynamic range of a DevelopmentPlatform. These rules are:

1. A date/time value is encoded as 0 if either
2. The value is equal to or earlier than 1601-01-01 12:00AM UTC.
3. The value is the earliest date that can be represented with the DevelopmentPlatform’s encoding.
4. A date/time is encoded as the maximum value for an Int64 if either
5. The value is equal to or greater than 9999-12-31 11:59:59PM UTC,
6. The value is the latest date that can be represented with the DevelopmentPlatform’s encoding.
7. A date/time is decoded as the earliest time that can be represented on the platform if either
8. The encoded value is 0,
9. The encoded value represents a time earlier than the earliest time that can be represented with the DevelopmentPlatform’s encoding.
10. A date/time is decoded as the latest time that can be represented on the platform if either
11. The encoded value is the maximum value for an Int64,
12. The encoded value represents a time later than the latest time that can be represented with the DevelopmentPlatform’s encoding.

These rules imply that the earliest and latest times that can be represented on a given platform are invalid date/time values and should be treated that way by applications.

A decoder shall truncate the value if a decoder encounters a DateTime value with a resolution that is greater than the resolution supported on the DevelopmentPlatform.