ICAD 6 does not map the screen to output colors to allow black and white printing - no matter how the print style tables are set or applied, I haven't been able to generatoe black and white prints. Suggestions?

That should work - edit the plot style table - form view - plot style. The default output color is "use object colour", click on the top colour then shift-click on the bottom to highlight them all, change it to black. Save the ctb.
Although a mate of mine has a laser printer and we haven't been able to print varying line thicknesses on that.

Why cannot line widths work on monochrome laser printers in V6. It used to work fine in V5. Is there any way of using the V5 printer control in V6 to allow B&W line widths?

Actually he has V5, I have seen the problem with Laser printers before but never had it with any (non-laser printer) of mine.

I'm using Icad 6 and an HP Laserjet 4ML. Line widths print fine.

Sorry, should have been more clear. My laser printer is not HPGL. However, it used to work on ICad5

Having spent a large chunk of time playing with all the alternatives, the problem with printing line weights comes down to the handling of text.

I use a colour based line weight table for a monochrome Laser printer emulating PCL 5e. If the use lineweights tab is checked, the lineweights come out according to colour but text all comes out at the thinnest weight for the text style regardless of colour. ISOCP and Romans are hairline thick and Arial is much too thick for dimensions. If the use lineweights tab is not checked, the Romans text style is a good thickness (prints at the lineweight of the thickest line) but all lines are the same thickness as the thickest line regardless of colour. Arial is so thick it is hard to read in small fonts.

Any suggestions?