@rohit_prajapati, you enterede forum of SAS community / SAS programming.
Your question is pure logical.
Anyhow - you are talking about periods. Period unit shoul be days or months etc.
otherwise it should be given as tow dates.
What do you mean by TRTSEQ -? Do you mean the days between the two treatments ?
or the difference length (days / months ...) of the two periods ?
If you answer above questions, I believe you'll be able to come to conclusion by yourself.