The -A switch

• Assigns an attribute to each triangle that identifies what segment-bounded region each triangle belongs to. (See the .ele file format description for a description of triangle attributes.)
• Attributes are assigned to regions by the .poly file; see the .poly file format description for details.
• If a region is not explicitly marked by the .poly file, triangles in that region are assigned an attribute of zero.
• The -A switch has an effect only when the -p switch is used and the -r switch is not.