I haven't heard that term, but it probably refers to PCB CAD [Computer Aided Design]. I've used two mainstream software packages, so for, to do PCB design: Eagle CAD, and currently, Dip Trace. Both have a limited freeware version.
Eagle CAD is very powerful but it is not "CUI" (Common User Interface), so you have to learn a different GUI paradigm to use it. Dip Trace isn't quite as feature rich as Eagle CAD, but the interface is easier for us "Windows Trained" folks to use. Example: DipTrace uses the familiar, left-click to select, right-click to access context sensitive pop-up menu items. It's been awhile since I've used Eagle CAD, and every time I come back to it, I have to learn the interface all over again, because it is so different from every other Windows program. In fact, I can't even remember enough to give an example, here.
But, there is a really good tutorial for Eagle CAD at SparkFun.com:
http://www.sparkfun.com/tutorials/108.
DipTrace comes with a tutorial, and it isn't bad, but it's a slightly awkward translation from, I believe, German, so you have to use a bit of imagination to figure out what is being said.
Bottom line, though: I have successfully designed somewhat complex PCBs using both Eagle CAD and DipTrace.
I began my PCB design career on PCB123, freeware that produced output only for the Sunstone PCB fabrication house. I had several designs on that format as well as a library of components of my own design. Then they upgraded the software and suddenly all my work was obsolete, as they didn't make it backwards compatible. I was furious, and swore i would never use PCB design software that didn't produce output that could be used at any PCB fabrication facility (i.e. Gerber files, or the like). Thus my migration to Eagle and then DipTrace. PCB123 has, since, corrected their omission, but once burned...
