These parameters are used to select how the line of dashes should be created. Dashlen is the length of the dash and Gaplen is the length of the gap between a dash and the next one all within a line of dashes. Dashlen defaults to 1 and Gaplen defaults to zero. These parameters are used to select the spacing and thickness of the lines being used to cross-hatch the image. Spacing the distance between a line of dashes and the next one.
Thickness is the width of the line of dashes.
Spacing defaults to 1 and Thick defaults to 2. Selecting Effect then exits the params prompt and allows ZIP to cross-hatch the image. From left to right, original Landsat TM Band 4 modified using a PC drawing package and image after cross-hatching.