WTS(Q) means for some variable Q , let suppose many transactions performed write , but out of those the time stamp of 'most new'(whose TS is largest of all other transaction's TS) process is considered as Write TS for variable Q means WTS(Q).
Now let suppose there will now many transaction , those're waiting for R/W variable Q , then it's basic rule of time stamp protocols that transaction with greater TS value (fresh process then process who updated WT(Q) last time) will be able to perform R/W on Q
So TS(Ti)>=WTS(Q) then Ti would be able to perform R/W on Q and WTS(Q) will be updated with TS of this process Ti .
For example let suppose there are 3 processes (T1,T2) with TS 10,20 respectively. If T1 performed write of variable then WTS(Q)=10 , now let suppose T2 now wish to perform write on variable Q , then can it perform TS(T2)=20>10 means yes it can perform and hence it will update WTS(Q) with 20. now let suppose again T1 want to perform read on variable Q. then can it perform? TS(T1)=10 is it greater than WTS(Q) which is 20? No. so this read can't happen...hope you got it now.
