This "Trim" function enables you to define a geographical area and to remove index entries outside of that area.

Note that the actual topographic elevation data files are not affected. Only the index entries are removed. Using the smaller index will usually improve the performance of TAP functions using the topographic data.

You can always use the Index function to add files back into the index.

When you click the "Trim Topo Data Index" button, you will be prompted to define the area you want:

If the "Use Boundary" checkbox is not checked, you can enter the latitude and longitude limits. You can also use the Template Lookup button to open the Area Template database to select an existing area definition.

If you click the "Use Boundary" box, you will be prompted to select a boundary file and an area object in the file:

When you click the Continue button, the file and object name will be displayed:

Note also that the coordinate limit values are updated to show the bounding rectangle around the object. The coordinate limits cannot be edited if the Use Boundary box is checked.

When you click the Continue button, you will be prompted for the type of trim you want to perform.  Based on the area selected, you can choose to delete index entries for all files outside of the area or to delete entries inside the area.

Note that index entries for topo data files that intersect a boundary (such as a file on the border of a state) are not deleted for either the "inside" or "outside" selections.

When you click the OK button, the index database will be searched and topo data files for areas outside of the specified limits will be removed from the index:

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