The number of C(0) block interface conditions, or cuts, is specified in the "general input" section (BOUNDARY AND CUT CONTROL) by the parameter CUTBCS. Cut conditions are specified in the input file after the general control data and after the boundary conditions. The first line of input for this section is a comment line (the $ delineator is not required). There must be a pair of cut condition input lines for each cut condition, in order to define the blocks that are to exchange data across the cut boundary. Each cut pair may be input in either order.

Example: (Comment line and pair of cut condition lines)

CUT NAME: CHARACTER STRING; string of up to 10 characters indicating the name of the cut condition. Both sides (that is, both lines) must have the same string. NOTE: The string C-PERIODIC is reserved to indicate that the cut is spatially periodic along a given Cartesian coordinate direction, and the string P-PERIODIC is reserved to indicate that the cut is spatially periodic in a Polar (rotated) geometry. These strings may not be used arbitrarily.

BLK: INTEGER; Block number that the cut condition applies to.

FACE:CHARACTER STRING; Face that the cut condition is to be applied on.
I = I constant boundary
J = J constant boundary
K = K constant boundary

PLACE:CHARACTER STRING; Cut condition location.
MIN = Cut condition at minimum face
MAX = Cut condition at maximum face

DIR1:CHARACTER STRING; Direction "1" for defining the cut window (e.g. for FACE 'I', DIR1 would be either 'J' or 'K').
I = I direction
J = J direction
K = K direction

BEG:CHARACTER STRING; Grid point at which to begin cut condition which runs in the direction specified by DIR1.
MIN = Start at minimum index of DIR1
MAX = Start at maximum index of DIR1
25  = Start at index 25 of DIR1

END:CHARACTER STRING; Grid point at which to end cut condition which runs in the direction specified by DIR1.
MIN = End at minimum index of DIR1
MAX = End at maximum index of DIR1
65  = End at index 65 of DIR1

NOTE 1: BEG does not have to be less than END, but BEG cannot equal END.

NOTE 2: The sequence (DIR1, BEG, END) must be repeated for DIR2.

IN-ORDER:INTEGER; Indicates whether the cut is to be propagated into the interior of the block as a part of the initialization process, and the order it is to be used in the initialization process. 0 = Do not use for initialization
1,2,3, ... = Propagate the cut into the block interior as a part of the initialization process where the number indicates the order in which to use the cut in that process.

NOTE: All cuts must have an IN-ORDER number assigned to them! If the cut is applied to an IMIN face it will be propagated in the positive I direction from the IMIN boundary to the IMAX boundary.

The only constraint imposed on the cut condition is that the same number of points must be spanned by matching coordinates on each side of the cut. The input routine checks for this and will stop and flag any cut that has unmatched points.