Question on filing revised it return

I Read about filing Revised IT Returns Rule that say's "Revised return can be filed at any time before the expiry of one year from the end of the relevant assessment year or before the completion of the assessment, whichever is earlier".  What is the meanaing of "before the completion of assesment", in my case I have filed the return for AY 2015-16 before the due date, ITR V sent to IT department and then I received Intimation under Section 143 (1) which shows the IT computation by IT department unders section 143 (1). Does this mean Assesment is complete ? and i can't file revised return ?

Thanks in advance

Lingaraju