Additional pattern cells are created just as all other cells are. Here are some guidelines to follow and restrictions to be aware of when creating area pattern cells:

• Area pattern cells should contain at least one full cycle of the pattern in both the horizontal and vertical directions.
• The cell range is used to determine the pattern matrix size. If you want unused space at the pattern boundary, place point elements (zero length lines) to expand the pattern range. Point elements are not patterned.
• If the cell is created as a point cell, the pattern components are placed on the Active Level using the color and line weight of the active symbology. The pattern will be on the same level as the element being patterned. If the cell is created as a graphic cell, the pattern elements are placed with the same symbology and on the same level as the element being patterned.
• The Pattern Area tool handles horizontal or vertical lines that span the entire pattern cell in a special manner. Instead of placing many contiguous line segments to create the pattern, these lines are extended through the entire pattern area. This results in a substantial increase in patterning speed and also requires much less room in the DGN file.