Environment Root

The SEDRIS Data Representation Model APPENDIX A - Classes Environment Root

Class Name: Environment Root

Superclass - <SEDRIS Abstract Base>

Subclasses

This DRM class is concrete and has no subclasses.

Definition

An instance of this DRM class is the aggregating object for the <Feature Hierarchy> instance and/or <Geometry Hierarchy> instance that represent the instantiation of a collection of all data in a common SRF in a given transmittal. An <Environment Root> instance is the starting point for all DRM objects in the same SRF in a transmittal.

Primary Page in DRM Diagram:

Secondary Pages in DRM Diagram:

Example

That portion of a transmittal that represents the Earth.
Consider a transmittal representing an area of North America that straddles two UTM zones. The <Transmittal Root> instance has two <Environment Root> components, one for each of the two UTM zones.

FAQs

Is a transmittal required to contain <Environment Root> instances?: No. For example, a valid transmittal may have a <Transmittal Root> instance that specifies only <Library> components, such as a <Transmittal Root> instance with a <Model Library> component but without any <Environment Root> components.
May a data provider supply multiple <Environment Root> instances in the same transmittal?: Yes, provided that the <Environment Root> instances comply with <<Environment Root SRF>>.
Why does an <Environment Root> instance have at most two <Hierarchy Summary Item> components?: See <<Hierarchy Summary Constraints>>.
Can an <Environment Root> instance have both <Hierarchy Summary Item> and <Primitive Summary Item> components (as opposed to either/or)?: Yes.

Constraints

Composed of (two-way)

zero or more <Base Time Data> instances¹
zero or one <Feature Hierarchy> instance
zero or one <Geometry Hierarchy> instance
a bounded set of 0..2 <Hierarchy Summary Item> instances²
zero or one <Interface Template> instance³
zero or more <Primitive Summary Item> instances
one <Spatial Extent> instance⁴

Composed of (two-way metadata)

zero or one <Data Quality> instance
zero or one <Identification> instance

Component of (two-way)

one <Transmittal Root> instance

Inherited Field Elements

This class has no inherited field elements.

Field Elements

SE_SRF_Context_Info	srf_context_info;	⁵

Notes

Composed of Notes

Base_Time_Data

These <Base Time Data> components are present only if they differ from the <Base Time Data> components of the <Transmittal Root> aggregate of the <Environment Root> instance.

Hierarchy_Summary_Item

The presence of these components depends on the <Feature Hierarchy> component and <Geometry Hierarchy> component. See <<Hierarchy Summary Constraints>> for details.

Interface_Template

If present, the <Interface Template> component provides access to all <Variable> instances defined within the scope of the <Environment Root> instance, if any. If there are such <Variable> instances, an <Interface Template> component shall be present; otherwise, it shall not be present.

Spatial_Extent

The <Spatial Extent> component specifies the spatial extent of the <Environment Root> instance, defining the maximum spatial extents of the component objects.

Fields Notes

srf_context_info

The srf_context_info field specifies the SRF within which all content of the <Environment Root> instance is defined.

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Last updated: July 26, 2006