TEX1J desc 'Job Start'
MEX1J desc 'Job 2'    Pred TEX1J
MEX2J desc 'Job end'  Pred MEX1J, MEX2J
# MEX1J must appear after TEX1J because it depend on TEX1J
# MEX2J must appear after TEX1J and MEX1J 
from a hash defined like this:
%hash={
  'MEX1J' => { 
    'desc' => 'Job 2' 
    'pred' => [TEX1J],
  },
  'MEX2J' => { 
    'desc' => 'Job end'
    'pred' => [TEX1J,MEX1J], 
   },
  'TEX1J' => { 
    'desc' => 'Job start'
    'pred' => [], 
   }
}