The various regions are described in terms of differences, intersections and unions of bodies. As in the case of body description, the user has the choice between free format and two kinds of fixed format. One of the latter is the traditional format used by the original Combinatorial Geometry as implemented for example in MORSE. The other fixed format is similar to it, but has been extended to allow body numbers larger than 10000. Both fixed formats are now superseded by the more convenient free region input format, recently introduced. Free format is based on body mnemonic "names" instead of sequential numerical identifiers and allows the use of parentheses to perform more complex boolean operations. However, the two fixed formats are still available for back compatibility reasons. With any input format, a line having an asterisk (*) in column 1 is treated as a comment card.
Previous Index Next