5.1.4 Volumes

Volume ( expression ) = { expression-list };

Creates a volume. The expression inside the parentheses is the volume's identification number; the expression-list on the right hand side should contain the identification numbers of all the surface loops defining the volume. The first surface loop defines the exterior boundary of the volume; all other surface loops define holes in the volume. A surface loop defining a hole should not have any surfaces in common with the exterior surface loop (in which case it is not a hole, and the two volumes should be defined separately). Likewise, a surface loop defining a hole should not have any surfaces in common with another surface loop defining a hole in the same volume (in which case the two surface loops should be combined).

Physical Volume ( expression | char-expression ) = { expression-list };

Creates a physical volume. The expression inside the parentheses is the physical volume's identification number (if a char-expression is given instead, a unique identification number is automatically created); the expression-list on the right hand side should contain the identification numbers of all the elementary volumes that need to be grouped inside the physical volume.