Class Name: Property Description

Superclass - Property

Definition

Used to elaborate a property attribute of an Aggregate Geometry or Aggregate Feature object and/or its component inheritance subtree by attaching Property Characteristic components and/or qualifying (limiting) Property Value components which meaningfully qualify the attribute identified by the Property Description.

Primary Page in DRM Diagram:

• 6

Secondary Pages in DRM Diagram:

• 4
• 8
• 20

Example

1. Consider a Union of Primitive Geometry containing Polygons, each of which has an emissivity applicable to the IR band only, where valid values are less than or equal to 1.0.
   

   The emissivity of each Polygon is applicable to the IR band only, because that property is so qualified by inheritance.

2. Consider a Union of Features containing various Primitive Features that must specify dewpoint temperature. For all the Primitive Features in this aggregate, the dewpoint temperature given was taken at a height of 10 meters above the surface of the terrain, and is of good quality.
   

   Since the Point Feature's Property Value describes EDCS_AC_DEWPOINT_TEMPERATURE, it inherits the following qualifiers:
   

   1. The dew point temperature measurement was taken at a height of 10 m above the surface, and
   2. The measurement is of good quality.

FAQs

How does an aggregate object use a Property Description?

In two ways, either separately or in combination.

1. An aggregate may use a Property Description to specify Property Characteristic components (such as maximum value for a quantity).
2. An aggregate might also use a Property Description's Property Value components to qualify a EAC code.

All objects in the component inheritance tree of the aggregate, as long as they have Property Value instances with a matching EAC code, are subject to the Property Descriptions and/or qualifying values.

I want to qualify an attribute A with two sets of qualifying Property Values, {b1, c1} and {b2, c2}. How do I associate two Property Values for A with the corresponding qualifier set?

You can't. This situation requires a Property Table.

Are there any restrictions on the Property Value components?

Only semantic restrictions. For example, it makes sense to limit the applicability of an electromagnetic emissivity value to a particular electromagnetic band. But it would be nonsensical to limit an electromagnetic band to a particular emissivity value.

Constraints

None.

Composed of (one-way)(inherited)

• optionally, some Property Characteristics

Composed of (one-way)

• optionally, some Property Values

Component of (one-way)

• optionally, some Aggregate Features
• optionally, some Aggregate Geometries
• optionally, some EDCS Use Summary Items

Inherited Field Elements

EDCS_AC_ID	attribute_code;	(notes)
EDCS_UNIT_ENUM	value_unit;	(notes)

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Notes

Fields Notes

attribute_code

 Specifies the meaning of the <Property>.
 The structure in attribute_code will contain an EAC.

value_unit

 Specifies the unit of measurement of the <Property>.

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