The SEDRIS Data Representation Model
APPENDIX A - Classes
Absolute Time Point

Class Name: Absolute Time Point

Superclass - <Time Point>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class is used to specify an absolute time (that is, Greenwich Mean Time (GMT), which is not relative to some other point in time).

<Absolute Time Point> provides

  1. a means to specify an absolute time (GMT) for [CSDGM]-compliant metadata, and


  2. a general-purpose mechanism for describing points in absolute (GMT) time.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

This class appears on only one page of the DRM class diagram.

Example

  1. The time at which an event happened in a historical database, i.e. Oct 3 17:56:47 GMT 1994, would be specified by an <Absolute Time Point>. For clarity, the time_significance field would be set to SE_TIME_SIGNIFICANCE_OCCURRENCE.

  2. The date and time when a SEDRIS transmittal was created.

  3. The date and time of observations.

FAQs

As a data provider, how do I indicate that the time information in an <Absolute Time Point> instance is not dependent on the year?

Setting year = -1 indicates this. Please note that this means that an actual date of 1 BCE (before common era) cannot be used. (It is anticipated that the only time a BCE date would be desired would be for astronomical Julian dates).

As a data provider, how do I indicate that the time information in an <Absolute Time Point> instance is not dependent on the month?

Setting month = SE_MONTH_ANY indicates this.

As a data provider, how do I indicate that the time information in an <Absolute Time Point> instance is not dependent on the day?

Setting day = -1 indicates this.

As a data provider, how do I indicate that the hour, minutes, and seconds fields are not applicable, that is, that the < Absolute Time Point> instance specifies only a date?

Setting hour = -1, minutes = -1, and / or seconds = -1 indicates that they are not applicable and are to be ignored.

Constraints

Component of (two-way)(inherited)

Component of (two-way)

Inherited Field Elements

SE_Time_Significance time_significance; (notes)

Field Elements

SE_Short_Integer year;
SE_Month month;
SE_Short_Integer day;
SE_Byte hour; (notes)
SE_Byte minutes; (notes)
SE_Long_Float seconds; (notes)

Notes

Fields Notes


time_significance

 This indicates the significance of the time information.

hour

 Use 24 hour clock for hour. The value shall be between -1 and 23,
 where a value of -1 indicates not applicable.

minutes

 The value shall be between -1 and 59,
 where a value of -1 indicates not applicable.

seconds

 Fractions provide higher accuracy if needed, e.g. milliseconds.
 -1 is the only negative value, and indicates not applicable.
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Last updated: October 1, 2002 Copyright © 2002 SEDRIS™