[Top] [Prev] [Next] [Bottom]

1.3 Conformance

This standard anticipates products that do not contain instances of all the specified information and syntactic forms. This portion specifies the conditions of conformance and the requirements of a conformance statement. This standard does not specify requirements for processing data into and out of the standard, therefore such processing cannot itself conform to this standard.

1.3.1 General Conformance.

Any product claiming conformance to this standard must follow the applicable requirements and specifications of parts 1, 2, and 3 with respect to both the syntax and the semantics of all included data elements.

1.3.2 Data Quality

This standard requires that spatial data to be transferred must include a report on data quality. This Data Quality Report must always accompany the data in a standard transfer. It consists of five portions described in detail in section 3, Spatial Data Quality: lineage, positional accuracy, attribute accuracy, logical consistency, and completeness. Where a spatial variation in quality is known, the quality report must record that variation.

1.3.2.1 Form of a Quality Report.

The Data Quality Report must always accompany the data in a standard transfer. Because the quality report will function in the assessment of fitness for use, it must also be obtainable in its entirety and separately from the actual data. This separate quality report may be issued as a Spatial Data Transfer or as a paper document.

1.3.2.2 Tests for Data Quality.

In sections 3.2, Positional Accuracy, 3.3, Attribute Accuracy, and 3.4, Logical Consistency, options are described for different categories of testing. Informed assessment of fitness for use is best served by the most rigorous types of tests.

1.3.2.3 Quality Overlays.

For those components of quality displaying spatial variation, a quality overlay system may be used. The producer of the quality report may choose to produce a comprehensive quality overlay describing all components of quality or separate overlays portraying various components. When the quality report is issued on paper, the quality overlays appear as diagrams with text labels or thematic map depictions. In digital form, the overlays must be encoded using the specifications of sections 4 and 5.

1.3.3 Conformance Statement

A statement claiming conformance to this standard must specify the profile and level of conformance for each applicable component of the Transfer Specification as defined in 1.2.4.

1.3.4 Transfer Specification Conformance Field

The Identification module of the Transfer Specification (5.2.1, Identification Module) includes a Conformance field. This field contains subfields for a object specification, external spatial reference conformance, a level of conformance to spatial feature definitions, coding conformance, and nongeospatial dimension specification. Each subfield is required to contain one of the values enumerated in 5.2.1.2, Conformance Field.

1.3.4.1 Object Specification.

The transfer must include the object specification described in 5.2.1.2.1, Object specification subfields.. This specification defines the domain of object types included in the transfer. Object types other than those identified in the Object Specification subfields must not be included in the transfer.

1.3.4.2 External Spatial Reference Conformance.

Whether or not one of the three recommended reference systems-- Geographics, UTM/UPS, or State Plane-- has been used, must be specified in the External Spatial Reference subfield of the Conformance field of the Identification module, as described in 5.2.1.2.2, as well as in the Reference System Name subfield of the External Spatial Reference module (5.2.4.2).

1.3.4.3 Features Level.

The level of conformance to the list of standard terms and definitions of spatial Entities and Attributes contained in part 2 of this standard must be specified in the Features Level subfield of the Conformance field of the Identification module. Each level has the meaning specified in 5.2.1.2.3.

1.3.5 Private Agreements

Private agreements limit the scope of the transfer and are discouraged. Recurring needs for similar private agreements should be referred to the maintenance organization for this standard.