Class Name: Relative Time Point

Superclass - Time Point

Definition

Used to specify a date and time relative to either a specified GMT (Absolute Time Point); or if an Absolute Time Point is not specified, relative to the simulation start time.

Primary Page in DRM Diagram:

• 20

Example

1. The Julian day of the year is 64 of 1997 and the time is 0630 GMT. The fields of the Relative_Time_Point are:
   delta_days = 64
   delta_hours = 6
   delta_minutes = 30
   delta_Seconds = 0
   and this class is associated with an Absolute Time Point with the following field values:
   year = 1997
   month = SE_USE_DAY_OF_YEAR
   day = 0
   hour = 0
   minutes = 0
   seconds = 0
   If year = -1, then the date can be applied to any year.
2. The date/time is a astronomical Julian day of 2449143.77083 (June 5, 1993 0630Z). Astronomical Julian dates are referenced to - 1 January 4712 BCE at 12Z. Also the fractional days must be converted to hours, minutes and seconds. The fields in the Relative Time Point object are:
   delta_days = 2449143
   delta_hours = 18
   delta_minutes = 30
   delta_seconds = 0.0
   and the fields in the associated Absolute Time Point are:
   year = -4712
   month = SE_JANUARY
   day = 1
   hour = 12
   minutes = 0
   seconds = 0
   
3. The time is 6 hours 25 minutes and 30 seconds after the start of the simulation. The fields of the Relative Time Point object are:
   delta_days = 0
   delta_hours = 6
   delta_minutes = 25
   delta_seconds = 30.0
   

FAQs

What is the purpose of this class?

This class provides a means to specify a time relative to another time. It can be used in the same manner as Absolute Time Point.

How do I indicate the Julian day of the year?

Use an association with an Absolute Time Point to indicate the reference date/time as 0Z 1 January of the appropriate year. If year = -1 then the date applies to any year. See example 1.

Can I specify times relative to date/times other than January 1?

Yes. See example 2.

How do I indicate a time relative to start of the simulation?

If a Relative Time Point does not have an Absolute Time Point component, then the time is relative to the start of the simulation. See example 3.

Constraints

• Legal Time Ranges
• Time Dependency

Composed of (one-way)

• optionally, an Absolute Time Point

Component of (one-way)(inherited)

• optionally, some Base Time Constraints Data
• optionally, some Environment Roots
• optionally, a Transmittal Root
• optionally, some Citations
• optionally, some Process

Inherited Field Elements

Field Elements

Notes

Fields Notes

time_significance

 Used to indicate the significance of the time information

delta_hours

 Must be between 0 and 23

delta_minutes

 Must be between 0 and 59

delta_seconds

 Must be between 0.0 and 59.0
 fractions provide higher accuracy if needed, e.g. milliseconds