ROWLOCK, UPDLOCK, READPAST Together

Hello,

I have noticed few queries uses ROWLOCK, UPDLOCK and READPAST query hints together. I want to know whats the difference between below 2 queries:

Case I

SELECT queries (ROWLOCK, UPDLOCK, READPAST) from table

Case II

SELECT queries (READPAST) from table

Will the Case II query get blocked because of any X lock on the table? We know it Case I query won't be blocked in this case.

Thanks

deepak