$title Exercise new XPRESS return code for unbounded MIP (MIP04,SEQ=525)

$onText
In the model we make sure the XPRESS link is properly handling the
XPRS_MIP_UNBOUNDED code - new in XPVERSION 22.

Contributor: Steve Dirkse, May 2011
$offText

variable x, y, z;
equations f, g;

f.. z =e= x + 2*y;
g.. x - 2*y =L= 2;

model m / f, g /;

solve m using mip max z;
abort$[m.solvestat <> %solveStat.normalCompletion%] 'Unexpected solvestat', m.solvestat;
abort$[(m.modelstat <> %modelStat.unbounded%) and (m.modelstat <> %modelStat.unboundedNoSolution%)] 'Unexpected modelstat', m.modelstat;