Instructions provided describe how to create and use a variable-depth masking layer in a ArcMap project. For more information regarding this cartographic effect, see the ArcGIS Desktop Help topic "Working with variable-depth masking".
Step 18 is missing from the ArcGIS Desktop Help.
Creating a masking layer
1. Click the Show/Hide ArcToolbox button on the Standard toolbar to show ArcToolbox.
2. Expand the Cartography tools.
3. Right-click the Feature Outline Masks tool. Click Open.
4. Click the Input Layer dropdown arrow and click a layer, or click the Browse button to select a layer file.
5. Type the name and location for the Output Feature Class or click the Browse button to create it.
6. Type a value in the Reference Scale parameter. If using an annotation layer, the reference scale will be automatically set.
7. Click the Spatial Reference Query button to set or change the spatial reference.
8. Type a value in the Margin parameter. Click the Margin dropdown arrow and select a unit of measure.
9. Click the Mask kind dropdown arrow and click a mask kind.
10. Optionally, check Create masks for unplaced annotation.
11. Click OK.
Using a masking layer
12. Click the Add Data button to add the masking layer to the data frame.
13. Right-click the data frame in the table of contents and click Advanced Drawing Options.
14. Check Draw using masking options specified below. Uncheck to turn off masking.
15. Click the layer being used as a mask in the Masking Layers list.
16. Check the layers to be affected by the mask in the Masked Layers list.
17. Click OK.
18. Uncheck the box for the layer being using as a mask in the Table of Contents.