If the (first) argument does not have the .pdf suffix, it is assumed to be the base file for a LaTeX document containing a prerequisite-chart description in prerex(5) format, to be edited using prerex(1). If a second argument is supplied, it is regarded as an included file containing the specific chart environment to be edited.
If no arguments are supplied, a file-opening dialog allows the user the specify the prerex(1) base file to be edited (or the PDF file to be viewed); if a separate chartfile is needed, vprerex(1) must be invoked wth two arguments on the command line.
If the mouse hovers over a hyperlink in the PDF viewing window, the cursor shape will change to a pointing finger and a tooltip will display the URI. If the PDF file displayed contains a chart generated using prerex.sty(7) and the background coordinate grid has been enabled, left-clicking the mouse on a course box, arrow mid-point, or background point will load the relevant coordinates into the X clipboard. The cursor shape changes to a plus-sign to indicate successful capture of the coordinates. Middle-clicking the mouse at the prerex(1) command-line will then paste those coordinates into a command being composed. If the chart file is regenerated, the updated document will be re-loaded.