Question on EB2 priority dates

[eastweststar]

Hello ,

I am from India. I read that EB2 priority date in Oct.2014 were 01 MAY 09.

1. This means that anyone who had priority date of 01 MAY 09 or BEFORE can file for I-485. Is my understanding correct ?

In November 2014, EB2 priority dates are retrogressed to 15 FEB 05.

2. What does this mean ? In one month you have priority date of May 2009 and in other again back to Feb 2005 ? So what about folks who have priority date between Feb 2005 and May 2009 ? Can they still file for Adjustment of Status because priority date was May 2009 in previous month or was it literally one month window that they give you for filing ?

What about people who filed I-140 and I-485 together. How does this affect them ?

I don't understand impact of switching priority dates by 4 years in consecutive months. Can anyone please elaborate how this affects the EB2 applications ?
Please give an example if possible.

Thanks very much !

[immihelp]

1. Yes, but in Oct 2014, and not now.
2. Those people between that time can't file for I-485 now.

If you filed for I-485 when your priority date was current still remains valid but will be hold if the priority date as per new visa bulletin is not current for you.