ORD file format: priorities and branching orders

The ORD file format supports priorities and branching orders.

If you use the 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

ORD files created using CPLEX versions 2.1 or earlier used a fixed format in which the various data fields were limited to eight characters in length and restricted to specific columnar positions in each line. The extensions provided in the more recent CPLEX ORD file reader allow for more descriptive names and greater overall input flexibility. Most fixed-format ORD files conform to the new format. Any files that do not conform can be converted to the more recent format using the convert utility that comes with the standard CPLEX distribution. Legacy file formats explains how to use that utility.