Logical Operators' inconsistent Behavior

Hi,

I need to understand the inconsistent behaviour of & and I operators when
used with NA.

The code below explains this inconsistency

TRUE & NA

[1] NA

FALSE & NA

[1] FALSE

TRUE & NA

[1] NA

FALSE | NA

[1] NA

TRUE | NA

[1] TRUE

TRUE == NA

[1] NA

FALSE == NA

[1] NA