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Topology error fixes
Release 9.3 Last modified May 14, 2009	Print all topics in : "Editing topology"

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Note: This topic was updated for 9.3.1.

NOTE: You can create simple, temporary topological relationships between features in ArcView. Creating or editing geodatabase topology requires an ArcEditor or ArcInfo license.

Most topology violations have that you can use to correct errors. Some topology rules, however, have no predefined fixes. Once you've discovered the topology errors, you can select the error on the map with the Fix Topology Error tool

, or select the error from within the Error Inspector and apply one of the fixes listed in the for that error type.

Learn more about topology rules

Polygon error fixes

Topology rule	Potential fixes
Must Be Larger Than Cluster Tolerance	Delete: The Delete fix removes polygon features that would collapse during the validate process based on the topology's cluster tolerance. This fix can be applied to one or more Must Be Larger Than Cluster Tolerance errors.
Must Not Overlap	Subtract: The Subtract fix removes the overlapping portion of geometry from each feature that is causing the error and leaves a gap or void in its place. This fix can be applied to one or more selected Must Not Overlap errors. Merge: The Merge fix adds the portion of overlap from one feature and subtracts it from the others that are violating the rule. You need to pick the feature that receives the portion of overlap using the Merge dialog box. This fix can be applied to one Must Not Overlap error only. Create Feature: The Create Feature fix creates a new polygon feature out of the error shape and removes the portion of overlap from each of the features, causing the error to create a planar representation of the feature geometry. This fix can be applied to one or more selected Must Not Overlap errors.
Must Not Have Gaps	Create Feature: The Create Feature fix creates new polygon features using a closed ring of the line error shapes that form a gap. This fix can be applied to one or more selected Must Not Have Gaps errors. If you select two errors and use the Create Feature fix, the result will be one polygon feature per ring. If you want one multipart feature as a result, you will need to select each new feature and click Merge from the Editor menu. Note that the ring that forms the outer bounds of your feature class will be in error. Using the Create Feature fix for this specific error can create overlapping polygons. Remember that you can mark this error as an exception.
Must Not Overlap With	Subtract: The Subtract fix removes the overlapping portion of each feature that is causing the error and leaves a gap or void in its place. This fix can be applied to one or more selected Must Not Overlap With errors. Merge: The Merge fix adds the portion of overlap from one feature and subtracts it from the others that are violating the rule. You need to pick the feature that receives the portion of overlap using the Merge dialog box. This fix can be applied to one Must Not Overlap With error only.
Must Be Covered By Feature Class Of	Subtract: The Subtract fix removes the overlapping portion of each feature that is causing the error so the boundary of each feature from both feature classes is the same. This fix can be applied to one or more selected Must Be Covered By Feature Class Of errors. Create Feature: The Create Feature fix creates a new polygon feature out of the portion of overlap from the existing polygon so the boundary of each feature from both feature classes is the same. This fix can be applied to one or more selected Must Be Covered By Feature Class Of errors.
Must Cover Each Other	Subtract: The Subtract fix removes the overlapping portion of each feature that is causing the error so the boundary of each feature from both feature classes is the same. This fix can be applied to one or more selected Must Cover Each Other errors. Create Feature: The Create Feature fix creates a new polygon feature out of the portion of overlap from the existing polygon so the boundary of each feature from both feature classes is the same. This fix can be applied to one or more selected Must Cover Each Other errors.
Must Be Covered By	Create Feature: The Create Feature fix creates a new polygon feature out of the portion of overlap from the existing polygon so the boundary of each feature from both feature classes is the same. This fix can be applied to one or more selected Must Be Covered By errors.
Boundary Must Be Covered By	Create Feature: The Create Feature fix creates a new line feature from the boundary segments of the polygon feature generating the error. This fix can be applied to one or more selected Boundary Must Be Covered By errors.
Area Boundary Must Be Covered By Boundary Of	None
Contains Point	Create Feature: The Create Feature fix creates a new point feature at the centroid of the polygon feature that is causing the error. The point feature that is created is guaranteed to be within the polygon feature. This fix can be applied to one or more selected Contains Point errors.

Line error fixes

Topology rule	Potential fixes
Must Be Larger Than Cluster Tolerance	Delete: The Delete fix removes line features that would collapse during the validate process based on the topology's cluster tolerance. This fix can be applied to one or more Must Be Larger Than Cluster Tolerance errors.
Must Not Overlap	Subtract: The Subtract fix removes the overlapping line segments from the feature causing the error. You must select the feature from which the error will be removed. If you have duplicate line features, select the line feature you want to delete from the Subtract dialog box. Note that the Subtract fix will create multipart features, so if the overlapping segments are not at the end or start of a line feature, you may want to use the Explode command on the Advanced Editing toolbar to create single part features. This fix can be applied to one selected Must Not Overlap error only.
Must Not Intersect	Subtract: The Subtract fix removes the overlapping line segments from the feature causing the error. You must select the feature from which the error will be removed. If you have duplicate line features, select the line feature you want to delete from the Subtract dialog box. Note that the Subtract fix will create multipart features, so if the overlapping segments are not at the end or start of a line feature, you may want to use the Explode command on the Advanced Editing toolbar to create single part features. This fix can be applied to one Must Not Intersect error only. Split: The Split fix splits the line features that cross one another at their point of intersection. If two lines cross at a single point, applying the Split fix at that location will result in four features. Attributes from the original features will be maintained in the split features. If a split policy is present, the attributes will be updated accordingly. This fix can be applied to one or more Must Not Intersect errors.
Must Not Have Dangles	Extend: The Extend fix will extend the dangling end of line features if they snap to other line features within a given distance. If no feature is found within the distance specified, the feature will not extend to the distance specified. Also, if several errors were selected, the fix will simply skip the features that it cannot extend and attempt to extend the next feature in the list. The errors of features that could not be extended remain in the Error Inspector dialog box. If the distance value is 0, lines will extend until they find a feature to snap to. This fix can be applied to one or more Must Not Have Dangles errors. Trim: The Trim fix will trim dangling line features if a point of intersection is found within a given distance. If no feature is found within the distance specified, the feature will not be trimmed, nor will it be deleted if the distance is greater than the length of the feature in error. If the distance value is 0, lines will be trimmed back until they find a point of intersection. If no intersection is located, the feature will not be trimmed and the fix will attempt to trim the next feature in error. This fix can be applied to one or more Must Not Have dangles errors. Snap: The Snap fix will snap dangling line features to the nearest line feature within a given distance. If no line feature is found within the distance specified, the line will not be snapped. The Snap fix will snap to the nearest feature found within the distance. It searches for endpoints to snap to first, then vertices, and finally to the edge of line features within the feature class. The Snap fix can be applied to one or more Must Not Have Dangles errors.
Must Not Have Pseudonodes	Merge To Largest: The Merge To Largest fix will merge the geometry of the shorter line into the geometry of the longest line. The attributes of the longest line feature will be retained. This fix can be applied to one or more Must Not Have Pseudonodes errors. Merge: The Merge fix adds the geometry of one line feature into the other line feature causing the error. You must pick the line feature into which to merge. This fix can be applied to one selected Must Not Have Pseudonodes error.
Must Not Intersect or Touch Interior	Subtract: The Subtract fix removes the overlapping line segments from the feature causing the error. You must select the feature from which the error will be removed. If you have duplicate line features, choose the line feature you want to delete from the Subtract dialog box. The Subtract fix creates multipart features, so if the overlapping segments are not at the end or start of a line feature, you may next want to use the Explode command on the Advanced Editing toolbar to create single part features. This fix can be applied to one selected Must Not Intersect or Touch Interior error only. Split: The Split fix splits the line features that cross one another at their point of intersection. If two lines cross at a single point, applying the Split fix at that location will result in four features. Attributes from the original features will be maintained in the split features. If a split policy is present, the attributes will be updated accordingly. This fix can be applied to one or more Must Not Intersect or Touch Interior errors.
Must Not Overlap With	Subtract: The Subtract fix removes the overlapping line segments from the feature causing the error. You must select the feature from which the error will be removed. If you have duplicate line features, choose the line feature you want to delete from the Subtract dialog box. The Subtract fix creates multipart features, so if the overlapping segments are not at the end or start of a line feature, you may next want to use the Explode command on the Advanced Editing toolbar to create single part features. This fix can be applied to one selected Must Not Overlap With error only.
Must Be Covered By Feature Class Of	None
Must Be Covered By Boundary Of	Subtract: The Subtract fix removes line segments that are not coincident with the boundary of polygon features. If the line feature does not share any segments in common with the boundary of a polygon feature, the feature will be deleted. This fix can be applied to one or more Must Be Covered By Boundary Of errors.
Endpoint Must Be Covered By	Create Feature: The Create Feature fix adds a new point feature at the endpoint of the line feature that is in error. The Create Feature fix can be applied to one or more Endpoint Must Be Covered By errors.
Must Not Self Overlap	Simplify: The Simplify fix removes self-overlapping line segments from the feature in error. Applying the Simplify fix can result in multipart features, which you can detect using the Must Be Single Part rule. The Simplify fix can be applied to one or more Must Not Self Overlap errors.
Must Not Self Intersect	Simplify: The Simplify fix removes self-overlapping line segments from the feature in error. Note that applying the Simplify fix can result in multipart features. You can detect multipart features using the Must Be Single Part rule. This fix can be applied to one or more Must Not Self Intersect errors.
Must Be Single Part	Explode: The Explode fix creates single part line features from each part of the multipart line feature that is in error. This fix can be applied to one or more Must Be Single Part errors.

Point error fixes

Topology rule	Potential fixes
Must Be Covered By Boundary Of	None
Must Be Properly Inside Polygons	Delete: The Delete fix removes point features that are not properly within polygon features. Note that you can use the Edit tool and move the point inside the polygon feature if you do not wish to delete it. This fix can be applied to one or more Must Be Properly Inside errors.
Must Be Covered By Endpoint Of	Delete: The Delete fix removes point features that are not coincident with the endpoint of line features. Note that you can snap the point to the line by setting edge snapping to the line layer, then moving the point with the Edit tool. This fix can be applied to one or more Must Be Covered By Endpoint Of errors.
Must Be Covered By Line	None

Topology error fixes