If you use the ILOG CPLEX MIP optimizer, the ORD file format is available to indicate priority orders and branching directions for specific variables. Variables that are not given an explicit priority or that do not appear in an ORD file are assigned 0 (zero) priority. An ORD file begins with a NAME indicator record and ends with an ENDATA record.

Integer variables are specified, one per line, with an optional branching direction (UP or DN) beginning in column 2 and 3. Names begin in column 5 or beyond. The variable name and its priority must be separated by one or more blank spaces.

Here is an example of an ORD file:

NAME
    x3                            10
 DN x5                             5
 UP x7
ENDATA