There are two types of discs produced by Prairie Works. One is a DVD video, often with actual video taken track side, and still photographs and illustrations all together on one disc with narration. Usually it is rare that video of the subject matter is available, so narration with still images predominates.
Then there are the CD-Rom books. The still photographs and illustrations are like looking through a book, there is an index and chapter headings and you 'turn' the pages. The images can be copied or printed for futher use. This is especially helpful to the modeler.
Some titles have both DVD and CD discs. The CD allows the viewer the opportunity to copy or print many of the images seen on the DVD. You can copy the image into an image editing software and 'take it from there'.
Most of the titles with a CD include images beyond equipment. There are images of calendar art, timetables, lanterns, passes, switch keys and such. You get many images for a very modest price!