Finally, it turned out that the whole question was a misunderstanding: I thought line width is ignored when printing to pdf. What actually happens is that when resolution of a graphic is increased (such as switching from display to pdf), lines that join data points on a plot (i.e. lines that are not straight) appear smaller (i.e. less width). Increasing line width from, say, 1 to 5 pixels appears as no perceptible change. Therefore, I thought line width is ignored. Actually, more substantial increases in line width (to 35 or 50 pixels) are necessary for the line to appear with similar width as on plots with poor resolution (i.e. that have less dots per inch). Dots and other symbols do not behave that way (their height appears in similar proportion, regardless of the graphic resolution). So, no format change is necessary to make lines on high-resolution plots appear with same width as on low-resolution, just a substantial increase in line width. Benno
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