PDM-UG: Date and Time

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This page belongs to the PDM Usage Guide.

The PDM Schema provides mechanisms for assignment of date and time to product data aiming at characterizing when some event or fact occurred. The specification of time is optional, i.e., in many cases only date is required. The applied_date_assignment entity allows for association of date with product data. The purpose of this association is specified by an instance of the entity date_role. As described later in this section, the PDM Schema supports a similar structure for concurrent assignment of date and time.

Dates are represented using the calendar_date entity, i.e., by specifying year, month and day. Time is unambiguously represented using the local_time entity, as it enforces the specification of the time zone, i.e., the offset to the coordinated universal time.

Contents

The Instance Model: EXPRESS entities and attributes

The EXPRESS entities and attributes essential to support the requirements for date and time are illustrated in Diagram 59.

Image:Diagram_59_Assignment_of_date_and_time_to_product_data.png
Diagram 59: Assignment of date and time to product data

Calendar date

The calendar_date entity is a subtype of date, which defines it as a day in a month of a year.

Attributes

  • The year_component attribute specifies the year in which the calendar_date occurs.
  • The day_component attribute specifies the day element of the calendar_date.
  • The month_component attribute specifies the month element of the calendar_date.


ENTITY calendar_date Attribute Population Remarks
year_component type: year_number Year is expressed as a four digits integer
day_component type: day_in_month_number Integer between 1 and 31, inclusive
month_component type: month_in_year_number Integer between 1 and 12, inclusive

===Preprocessor Recommendations=== The instance shall define a valid calendar date, i.e., it must take into account constraints related to the number of days in a month (e.g., in June the day_component must be an integer between 1 and 30, inclusive.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

Local time

The local_time entity represents an instance of time by expressing hour, minute and second in the local time zone and also specifying the offset to the coordinated universal time.

Attributes

  • The hour_component attribute specifies the number of hours.
  • The minute_component attribute specifies the number of minutes.
  • The second_component attribute specifies the number of seconds.
  • The zone attributes specifies the offset of the local time zone to the coordinated universal time.


ENTITY local_time Attribute Population Remarks
hour_component type: hour_in_day Integer between 0 and 23, inclusive, where midnight shall be represented by the value 0.
minute_component type: minute_in_hour Integer between 0 and 59, inclusive. This attribute is optional.
second_component type: second_in_minute Real between 0 and 59, inclusive. This attribute is optional.
zone type: entity= coordinated_universal_time_offset  

===Preprocessor Recommendations=== There are no specific preprocessor recommendations.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

Coordinated universal time offset

The coordinated_universal_time_offset entity specifies allows for relating a time to coordinated universal time by an offset. Coordinated Universal Time (UTC) is the international time standard, which was previously known as Greenwich Meridian Time (GMT).

Attributes

  • The hour_offset attribute specifies the number of hours by which a time is offset from coordinated universal time.
  • The minute_offset attribute specifies the number of minutes by which a time is offset from coordinated universal time.
  • The sense attribute specifies the direction of the offset.


</td> <tr> <td>minute_offset</td> <td>type: Integer</td> <td>Value must be between 0 and 59. This attribute is optional</td>

<tr> <td>sense</td> <td>type:ahead_or_behind= ENUMERATION</td> <td>May assume values ahead, behind or exact</td> </tr> </table> ===Preprocessor Recommendations=== There are no specific preprocessor recommendations. ===Postprocessor Recommendations=== There are no specific postprocessor recommendations. ===Related Entities=== There are no specific related entities.

Date and time

The date_and_time entity specifies time on a particular day.

Attributes

  • The date_component attribute specifies the date element.
  • The time_component attribute specifies the time element.


ENTITY coordinated_universal_time_offset Attribute Population Remarks
hour_offset type: Integer Value must be between 0 and 12
ENTITY date_and_time Attribute Population Remarks
date_component type: entity = date In the PDM Schema, it points to an instance of calendar_date.
time_component type: entity = local_time  

===Preprocessor Recommendations=== There are no specific preprocessor recommendations.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

Applied date assignment

The applied_date_assignment entity allows for association of date with product data.

Attributes

  • The assigned_date attribute specifies the date to be assigned to product data.
  • The role attribute specifies the purpose of the assignment of the date to product data.
  • The items attribute is a reference to the product data to which the date is being assigned.


ENTITY applied_date_assignment Attribute Population Remarks
assigned_date type: entity = date In the PDM Schema, it points to an instance of calendar_date.
role type: entity = date_role  
items type: date_item = SELECT SET [1:?]

===Preprocessor Recommendations=== There are no specific preprocessor recommendations.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

Date role

The date_role entity specifies a role for an applied_date_assignment.

Attributes

  • The name attribute defines a label by which the date_role is known.
  • The description attribute specifies text that characterizes the date_role.


ENTITY date_role Attribute Population Remarks
name type: label a string value
description type: text DERIVED

===Preprocessor Recommendations=== There are no specific preprocessor recommendations.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

Applied date and time assignment

The applied_date_and_time_assignment entity allows for association of date and time with product data.

Attributes

  • The assigned_date_and_time attribute specifies the date_and_time to be assigned to product data.
  • The role attribute specifies the purpose of the assignment of the date_and_time to product data.
  • The items attribute is a reference to the product data to which the date_and_time is being assigned.


ENTITY applied_date_assignment Attribute Population Remarks
assigned_date_and_time type: entity = date_and_time In the PDM Schema, the date_component attribute points to an instance of calendar_date.
role type: entity = date_time_role  
items type: date_item = SELECT SET [1:?]

===Preprocessor Recommendations=== There are no specific preprocessor recommendations.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

Date time role

The date_time_role entity specifies a role for an applied_date_and_time_assignment.

Attributes

  • The name attribute defines a label by which the date_role is known.
  • The description attribute specifies text that characterizes the date_role.


ENTITY date_role Attribute Population Remarks
name type: label a string value
description type: text DERIVED

===Preprocessor Recommendations=== There are no specific preprocessor recommendations.

===Postprocessor Recommendations=== There are no specific postprocessor recommendations.

===Related Entities=== There are no specific related entities.

The Instance Model: STEP exchange file format (ISO10303 Part 21 syntax)

#10 = PRODUCT_DEFINITION_FORMATION('02', 'lever modified', #20);
#20 = PRODUCT('K01-42051', 'Bicycle Bell RX25B', '', (#30));
#30 = PRODUCT_CONTEXT('', #40, '');
#40 = APPLICATION_CONTEXT('mechanical design');
#50 = PRODUCT_RELATED_PRODUCT_CATEGORY('part', '', (#20));
.
.
.
#920 = APPLIED_DATE_AND_TIME_ASSIGNMENT(#970, #930, (#10));
#930 = DATE_TIME_ROLE('creation date');

/* definition of date and time */
#970 = DATE_AND_TIME(#980, #990);
#980 = CALENDAR_DATE(1999, 14, 5);
#990 = LOCAL_TIME(0, 0, 0.0E+000, #1000);
#1000 = COORDINATED_UNIVERSAL_TIME_OFFSET(1, $, .AHEAD.);
Example 59: exchange file segment for date and time assignment
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