Prioritizing Elements in a 2D DGN File
This section assumes that the "Non-rasterized priority sort mode" pen table option is cleared. This is the default setting.
In a pure 2D DGN file, display priority is the preferred method for sorting elements. Display priority sorting is supported when printing in either rasterized or non-rasterized mode. When printing, designs making use of display priority do not consume any more memory than designs that do not use display priority. Display priority sorting in rasterized print mode is implemented by the graphics hardware and is more efficient than software sorting.
In a 2D design, the pen table priority output action simply replaces the effective display priority value (the sum of the reference, level, and base element priority values) of the element being modified.
Note that display priority can not be applied to 3D elements. In practice, 3D elements often appear in 2D designs. For example, cells from 3D cell libraries that are placed in a 2D design file are unaffected by pen-table-specified display priority.
A similar limitation applies to viewlets (3D references attached to 2D master models). In this situation, display priority cannot be used to prioritize elements across the 2D/3D reference boundary. For example, consider the common case of a pen table attempting to place text above all other element types. If the master model is listed last in the reference update sequence, the 2D master model elements will print on top of the text in the 3D reference despite the pen table's display priority assignments. This can be addressed by setting "Non-rasterized priority sort mode" in the pen table.