April 1993

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(ESRI Shapefile with ArcGIS .lyr and ArcView 3x .avl)

Overview

The Digital Quadrangle Template is used as the index layer for the QUAD and QUAD2 libraries at MassGIS, which store1:25,000 U.S. Geological Survey's Digital Line Graph (DLG)-based data. This digital quadrangle template comprises 211 quadrangles. The grid differs from the USGS Topographic Map Quadrangle Template, which is based on the 1:25,000 USGS 7.5 minute topographic quadrangles and used for paper maps. For most of Massachusetts, though, the paneling schemes are identical. The quadrangle panels and numbering scheme vary along the coast, primarily for the Cape and Islands quads. For details see the Index Map pdf format of ix_quad.pdf
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In ArcSDE the layer is named USGSGRID_POLY.

Production

The layer was created in coverage format by the ARC/INFO GENERATE command. Using the PROJECT command, the coverage was projected into Massachusetts State Plane Feet, NAD27. The coverage was then built and attributes added to the polygons to identify the digital quadrangles. One additional quad was added to the coverage for ease of processing some of the coastal data. This quadrangle (DIG-ID = 158-S), however, may not correspond to USGS DLG data.

Attributes

The polygon attribute table contains the two items to identify each quadrangle:
QUAD_NAME 25 25 C Quadrangle name
DIG_ID  5 C Quadrangle identifier; may have a -W,-E or other extension

Maintenance

This datalayer is being maintained by MassGIS.

Last Updated 5/31/2007