I seem to remember that my tech info leaned on the Ricke book and production catalogues but I have used other sources as well - notably Orrefors documentation.
Graal is the general term for glass which was made in two stages. First the core with a colour layer was cooled, the successive operation introduced a pattern into the colour layer by cold working, either with sand/ grit blasting, or by cut-to-clear. The cooled piece was then reheated, covered in clear glass, blown out and finished as usual. This explains why you can have "U" codes (=finished at the oven) on some Kraka glas, in stead of the "S" code you'd expect.
Now Kraka is one form of Graal whereby the colour core was broken open in a fishnet pattern. It is not the technique which uses an asbestos ready made net around a hot core, like Harrtil glass or Merletto - these techniques are not to be confused.
The Graal technique was specific for Orrefors, I do not believe anyone else used quite the same method.
Fishgraal, Slipgral (cut pattern), Ravenna (mosaic), Kraka (net-shape) and Ariel (entrapped air bubbles) are all variations on the same technical theme.