Medium Resolution Digital Vector Shoreline Digital Geography Metadata

Arc attributes found in the Medium Resolution Digital Vector Shoreline Digital Geography
*S_SCALE*	Map scale of the source chart from which the arcs were captured. From 1:10,000 to 1:600,000.
*S_CHART*	NOS chart catalog number for chart from which the arcs were captured. Charts included 11301 through 18800.
*S_DATUM*	Source chart horizontal reference datum.
	02	Horizontal Datum = NOS 1902.
	27	Horizontal Datum = NOS 1927.
	83	Horizontal Datum = NOS 1983.
*S_REV_DATE*	Source chart's date of revision. Any valid date string (mm/yy), 1/87 through 12/92.
*S_SOURCE*	Identifies method used to capture source data;
	1	Arc/Info-ArcEdit Heads Up.
	2	Hitachi CADCore Heads Up.
	3	Digitizing Table.
	4	Estimation or truncation arc added post capture. (*)
	5	Data obtained from the State of Florida.
*S_ARC_CODE*	Coding identifying the arc type;
	1	Shoreline data arc from capture process.
	3	Shoreline truncation arc -post capture addition.
	5	Shoreline estimation arc -post capture modification/addition. (*)
*S_INTEGRIT*	Qualitative assessment of arcs accuracy based on source media;
	1	Master compilation -heavy gauge mylar (0.007 in).
	2	X-drawing; reproduction of master on lighter grade(0.003) mylar.
	3	Water resistant paper.
	4	Data sourced from the State of Florida.
	5	Estimate or truncation arc.(*)
	6	Unknown. (*)
*REGIONLIST*	List of Coastal Assessment Regions (individual or combined list from the following);
	N	Polygons of the North Atlantic region.
	M	Polygons of the Middle Atlantic region.
	S	Polygons of the South Atlantic region.
	G	Polygons of the Gulf of Mexico region.
	P	Polygons of the Pacific region.
	L	Polygons of the Great Lakes region.
	U	Polygons within the US border, but not a part of the CAF.
	X	Polygons outside US boundaries.
NOTE:	*	Truncation arcs are arcs inserted into the data to provide continuity/closure in places where the cartographic information on the chart was incomplete. Often, small water bodies (rivers, streams, and creeks), in locations beyond the point of navigability are terminated to facilitate the insertion of non-cartographic information such as title blocks and notations. Continuity of the data, a requirement our data set specification, is interrupted at these locations if they are captured and retained as depicted on the navigation chart. To reestablish the necessary topological continuity an artificial closure arc is placed across the truncated section of shoreline. These arcs make no attempt to simulate the position of the missing shoreline section(s), but rather simply terminate the feature. To easily identify these arc features in the data field they are given the attribute codes: S_SOURCE = 4 and S_ARC_CODE = 3. Estimation arcs are used for two purposes: first, to fill in gaps in the shoreline as depicted on the chart (other than those areas which would be considered truncations), and secondly, to identify captured (digitized) shoreline arcs which have been modified in some way either for error rectification or edge matching adjustments. The span of these arcs range from five meters to several tens of meters in length. In the first case, estimator arcs attempt to simulate or mimic the actual shape or course of the coastline in the missing area. Insertion of these arcs into the data is done using heads up methods with the appropriate navigational chart(s) as a guide. In the second case, an existing arcs terminal to node is moved from its original captured location to a position where it can be connected to the concomitant arc's node from an adjacent chart. Additional vertices may then be added to replicate the course of the original information. Modification of existing arcs was carried out such that disruption of the information was minimized. Estimate arcs are identified in the data by the codes: S_SOURCE = 4, S_ARC_CODE = 5. If the accuracy of the data could not be assessed and thus categorized into one of the five qualitative integrity classes, the arc was classified with an integrity of unknown. Most of the arcs grouped into the unknown category were those captured early in the project. During that time source materials (primarily master compilations and X-drawings) were assumed to be of equal stability and accuracy. This was not, however, the case. Once this disparity was recognized, source tracking procedures were implemented and the integrity of the captured information, based on the stability and clarity of the source media was tracked and assessed.