For advanced use only. For the most part these are unnecessary and should be used only in special circumstances. Support for these may be discontinued. If you find a compelling use for any of them, please email email@example.com.
cmp=1 "CoMParator": This forces comparator mode, regardless of how many (0, 1, 2) molecule are prespecified.
nco=1 "No Comparator Option": When a single molecule is prespecified, don't offer a slot for a second molecule. Starting with PE 1.91, this is ignored, since the comparator option is no longer offered during startup on an intermediate page.
nrs=1 "No ReSize": Don't offer option to resize window. Starting with PE 2.2, this is ignored, because the new menu "Window size for new PE sessions" at the FrontDoor controls this.
x=1 "Expert mode": Forces expert mode. Not generally a good idea since the user can control this in Preferences.
nnw=1 "No New Window": Use with caution. When a link accesses pe.htm (the link should not specify a target window name!) a new window is automatically opened to guarantee that PE is not starting within a frame. If the hyperlink to pe.htm specifies a target window name which does not exist, and therefore the browser creates the target window, pe.htm will detect this and will not open an additional (unnecessary) window. If you specify nnw=1 and don't open a new window for PE, when the [Quit] button of PE is pressed, it will close its window (possibly the only window the browser has open).