If you use the ILOG CPLEX MIP optimizer, the MST file format is available to indicate MIP start values for specific variables, most commonly the integer variables. MST files are of the same format as SOL files. MST files written by ILOG CPLEX will have values only for the integer variables and members of special ordered sets (SOS). In contrast, SOL files have values for all variables.

MST file format also supports MIP starts from members of the solution pool. See details about the Concert Technology methods cplex.writeMIPStart and the Callable Library routine CPXmstwritesolnpool and CPXmstwritesolnpoolall, documented in their respective reference manuals.

The start values in an MST file are used only if the advanced indicator parameter is on (set to 1 (one) its default).

Here is an example of an MST file:

<?xml version = "1.0" standalone="yes"?>
<?xml-stylesheet 
href="https://www.ilog.com/products/cplex/xmlv1.0/solution.xsl" 
type="text/xsl"?>
<CPLEXSolution version="1.0">
 <header
   problemName="../../../examples/data/mexample.mps"
   objectiveValue="-122.5"
   solutionTypeValue="3"
   solutionTypeString="primal"
   solutionStatusValue="101"
   solutionStatusString="integer optimal solution"
   MIPNodes="0"
   MIPIterations="3"/>
 <quality
   epInt="1e-05"
   epRHS="1e-06"
   maxIntInfeas="0"
   maxPrimalInfeas="0"
   maxX="40"
   maxSlack="2"/>
 <variables>
  <variable name="x4" index="3" value="3"/>
 </variables>
</CPLEXSolution>