Accessing Data Fields and Values

In Shapefile

Attribution in One File

Example: To find an attribute value and description for the road network, select any record in the *nw.dbf file:

FILE NAME	FILE IDENTIFIER	ATTRIBUTE FIELD CODE	ATTRIBUTE FIELD VALUE	ATTRIBUTE VALUE DESCRIPTION (FROM MULTINET® SHAPEFILE FORMAT SPECIFICATION DOC)
Network	NW	FOW	10	Form of Way; 10: Part of a Slip Road

Attributes in Extended Files

MultiNet Shapefile provides the *ea file to store extended attributes and the *nm file to store extended name information for some features. The linkage is made via the feature IDs.

With the release of MultiNet 3.6 two new Shapefiles, *as and *av, define attribution for some features. Points of Interest attribution is an example.

Example: To find POI attributes, start with the *pi file.

Note: In the following example screen shots, not all file fields are shown. Only the ones necessary to describe the file linkage to find attribution are included.

Figure: Shapefile Attribution in Extended Files - 1

From the pi table the ID (10200200006238 (in red)) is used to link to the *as table. See figure below. FEATTYP 8099 is the Mountain Peak feature.

Figure: Shapefile Attribution in Extended Files - 2

The pias table links the the Mountain Peak feature to two attributes: 6P (Height of Mountain Peak) and NG (POI Service Group). These attributes are linked via ATT_IDs 102000000000005 (in green) and 102000000000006 (in brown), respectively to the attribute value table. The attribute values are found in the piav table. See figure below.

Figure: Shapefile Attribution in Extended Files - 3

The piav table provides the values for the attributes:

6P – Height of Mountain Peak = 2405 (meters);
NG – Feature Mountain peak belongs to Service Group 12 (Label Features).

See the MultiNet Points of Interest Specifications for details concerning POIs.

In GDF-AS

Multiple records (GDF-AS) are required in order to decode fields and values in GDF-AS format. Dataset records are contained in individual files with the extension ".gdf."

See the MultiNet GDF-AS Specification document for details on the GDF-AS format.

See also Data Content - GDF-AS in this user guide: for descriptions of the record types.

Example: To find an attribute value and description for a road in a GDF-AS file, search the attribute records for the road feature:

Select a Line Feature record type 52 in the *.gdf file that contains a Road Element feature code 4110 and obtain the Segmented Attribute Record ID (SATT_ID):
52 300105762 41100 1 417329728 0 1 92832 510093262 5100714000
The Segmented Attribute Record ID is 92832. Search record type 44 for ID 92832. Attribute types (ATT_TYPE) and values (ATT_VAL) for the Road Element are defined in the record:
44 92832 9FC 7 8C 4 HS 1
To find the definition of the attribute type FC from the last step, go to record 05, Attribute Definition Record. Attribute codes come immediately after the "05" in those records:
05FC10N Functional Road Class 0
To find the definition of Functional Road Class attribute value 7, go to record 18, Attribute Value Definition Record:
18FC7 ENGLocal Roads of Minor Importance 0

In GDF-AR

Multiple files (GDF-AR) are required in order to decode fields and values of a dataset.

See the MultiNet GDF-AR Specification document for details on the GDF-AR format.

Example: To find an attribute value and description for a road in a GDF-AR file, you need to find the attribute records for a road feature:

Select a record in the Line Feature Record file (*.LIN) that contains a Road Element feature code 4110. Obtain the Line Feature Item ID (LneItemId):
84062 129575 300095676 141100 2 1 510095260 5100952560
The Line Feature ID is 300095676. Search the Feature Attribute Reference file for lines (*.FA2) and find the Line Feature ID. Find the ID for the corresponding Attribute Set Item ID (AttItemid).
84062 129575 300095676 197437
The Attribute Set Item ID is 197437. Search the Attributes file (*.ATR) for the Attribute Set Item ID. Attribute types (AttTyp) and attribute values (AttValue) for the Road Element are defined in the record.
84062 129575 197437 1FC8

84062 129575 197437 2DS2

84062 129575 197437 38C6........

Unlike GDF-AS, value definitions need to be accessed outside of the files. For a list of attribute names and codes, refer to the allcodes database included in your data delivery.