ILR :Absence outside of UK Limit 180 or 450 days??

Hello

I know that no rule mentioned in the UKBA website for the minimum number of days to be outside UK for last 5 years of stay for ILR.

For naturalization its 450 days and its clearly mentioned.
http://www.ukba.homeoffice.gov.uk/briti ... cesfromuk/

It was no where mentioned for the ILR. However I could see many people posting it as 180 days during last 5 years which comes down as 36 days per year. Somehow I feel suspicious about this 180 days limit. Any link or proof to say that it is 180?

How can one only can have 180 days for ILR and immediately 450 days in the next year when they apply for naturalization?It sounds no logic.

Kindly clarify.
Haris

Depends on category.