set i product type /1*2/, t months /1*3/;

table c(i,t) production cost 1 2 3 1 30 31 32 2 28 30 27;

table d(i,t) demands 1 2 3 1 400 5000 750 2 850 1200 1200;

parameters h(i) /1 0.9,2 0.75/, p(i) /1 0.8,2 1/, beg(i) /1 100,2 150/, ca(t) /1 3010,2 3500,3 3000/; variable z; positive variables X(i,t),IN(i,t); equations obj c1 c2 ; obj..z=e=sum((i,t),X(i,t)*c(i,t))+sum((i,t),IN(i,t)*h(i)); c1(i,t)..IN(i,t-1)+X(i,t)=e=d(i,t)+IN(i,t); c2(t)..sum((i),X(i,t)*p(i))=L=ca(t); model rec1_3 /all/; FILE OPT Cplex option file/cplex.opt/; PUT OPT; PUT'objrng all'/ 'rhsrng all'/; PUTCLOSE OPT; rec1_3.optfile=1; rec1_3.dictfile=4; option iterlim =100000000; option reslim=100000000; solve rec1_3 using LP minimizing z; display X.L,z.L;

Can you explain step by step where it is written in bold? (for example, what does name.dictfile=4; mean? etc.)