model 

{for (i in 1:n)
   {c[i]~dcat(q[])
    y[i]~dnorm(mu[c[i]],tau[c[i]])
    }

 for (j in 1:2)
   {tau[j]~dgamma(1,1)
    }

 mumean[1]<-mu0-2
 mumean[2]<-mu0+2
 for (j in 1:2)
     {mudash[j]~dnorm(mumean[j],3.3)
      }
 mu[1:2]<-sort(mudash) # This imposes the order constraint.

 mu0~dnorm(4.0,p.mu)
 p.mu<-0.1

 pi~dbeta(3,3)
 q[1]<-pi
 q[2]<-1-pi
 }