These tools date back to the early 80's. Log supports schematic entry for documentation, simulation, and netlist creation. Schematic printouts can be previewed on-screen, and Postscript and HPGL output. Numerous other supporting tools. PCB Software A suite of PCB layout tools, from schematic capture, to auto-routing, to layout.
Documentation seems very good.
File formats are well documented. Electric includes a fairly extensive manual. This is a very small C program to convert HPGL or DXY files to PostScript. This is from comp.sources.misc, Volume 1, 1987. This would require a lot of work to make useable.