question: public static void writeBranchRatesModelRef ( PartitionClockModel model , XMLWriter writer ) { String tag = "" ; String id = "" ; switch ( model . getClockType ( ) ) { case STRICT_CLOCK : tag = StrictClockBranchRatesParser . STRICT_CLOCK_BRANCH_RATES ; id = model . getPrefix ( ) + BranchRateModel . BRANCH_RATES ; break ; case UNCORRELATED : tag = model . isContinuousQuantile ( ) ? ContinuousBranchRatesParser . CONTINUOUS_BRANCH_RATES : DiscretizedBranchRatesParser . DISCRETIZED_BRANCH_RATES ; id = model . getPrefix ( ) + BranchRateModel . BRANCH_RATES ; break ; case RANDOM_LOCAL_CLOCK : tag = RandomLocalClockModelParser . LOCAL_BRANCH_RATES ; id = model . getPrefix ( ) + BranchRateModel . BRANCH_RATES ; break ; case FIXED_LOCAL_CLOCK : tag = LocalClockModelParser . LOCAL_CLOCK_MODEL ; id = model . getPrefix ( ) + BranchRateModel . BRANCH_RATES ; break ; case AUTOCORRELATED : tag = ACLikelihoodParser . AC_LIKELIHOOD ; throw new UnsupportedOperationException ( "Autocorrelated relaxed clock model not implemented yet" ) ; default : throw new IllegalArgumentException ( "Unknown clock model" ) ; } writer . writeIDref ( tag , id ) ; }
target:  Write the branch rates model reference.