Standard internal rules for choke, spread, and centerline trapsBy default, Microsoft Publisher overprints black lines, fills, and imported pictures when these objects have a black percentage equal to or greater than the black overprint threshold value.
For other lines and for borders, Publisher traps using its internal trapping rules. Depending on the relationship of the border to adjoining or overlapping objects, Publisher may trap the outside of the border differently from the inside of the border.
Standard internal rules for choke, spread, and centerline traps
Spreads trap a dark background object to a lighter foreground object by the default trap width. For process colors, the darkest CMYK ink values are taken from the lighter color and extended onto the background. For adjoining spot colors, Publisher spreads the foreground color at the default trap width.
Chokes trap a dark foreground object to a lighter background by the default trap width. For process colors, the darkest CMYK ink values are taken from the lighter color and extended onto the foreground color. For adjoining spot colors, Publisher extends the background color at the default trap width.
Centerlines trap objects that have similar luminance values. For process colors, the darkest CMYK ink values are taken from each object; the resulting trap color is extended in both directions from the centerline of the object by one-half the default trap width. For adjoining spot colors, Publisher extends both the foreground and background colors from the centerline of the object by one-half the default trap width
Standard internal rules for trapping borders and BorderArt
Borders around a frame filled with color will trap to the fill color based on Publisher's standard internal rules.