This 4 year period info is new to me and I do apprecaiteyou told me that.I did not find that information from USDHS website.
-See this website:
http://immigrationroad.com/green-card/citizenship.php
"......
So in the next 4 year period, my understanding is that I have to stay at least half of the time in the USA and do not stay out of USA for more than 6 months each time I am out of USA to be qualified for the US citizenship application.
Is that correct?
-Correct.
Is there any other matter that I have to be aware of ?