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

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

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

Example

  1. Consider a SEDRIS transmittal constructed from a historical database, in which the time at which an event happened is recorded as Oct 3 17:56:47 GMT 1994. In the SEDRIS transmittal, this information is specified by an <Absolute Time Point> instance with time_significance = SE_TIME_SIGNIFICANCE_OCCURRENCE, as follows.

    time_significance = SE_TIME_SIGNIFICANCE_OCCURRENCE
    year =1994
    month = SE_MONTH_OCTOBER
    day=3
    hour=17
    minutes =56
    seconds =47.0

  2. Consider a SEDRIS transmittal for which the data provider wishes to represent the date and time when the transmittal was created - in this example, Mar 23 15:18:33 GMT 2003. In this case, the data provider would create an <Absolute Time Point> instance with time_significance = SE_TIME_SIGNIFICANCE_CREATION_DATE and the other field values set appropriately, as follows.

    time_significance = SE_TIME_SIGNIFICANCE_CREATION_DATE
    year =2003
    month = SE_MONTH_MARCH
    day=23
    hour=15
    minutes =18
    seconds =33.0

    This <Absolute Time Point> instance would then be attached as a component of the transmittal's <Transmittal Root>.

  3. The date and time of observations.

FAQs

How may a data provider 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).

How may a data provider indicate that the time information in an <Absolute Time Point> instance is not dependent on the month?

Setting month = SE_MONTH_ANY indicates this.

How may a data provider indicate that the time information in an <Absolute Time Point> instance is not dependent on the day?

Setting day = -1 indicates this.

How may a data provider 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: May 15, 2003 Copyright © 2003 SEDRIS™