Infix operators take two arguments, one on either side. Operators
have precedence, but operations with equal precedence are performed left
to right. Apart from
+ or -, both arguments must be
absolute, and the result is absolute.
The comparison operators can be used as infix operators. A true results has a value of -1 whereas a false result has a value of 0. Note, these operators perform signed comparisons.
These two logical operations can be used to combine the results of sub expressions. Note, unlike the comparison operators a true result returns a value of 1 but a false results does still return 0. Also note that the logical or operator has a slightly lower precedence than logical and.
In short, it's only meaningful to add or subtract the offsets in an address; you can only have a defined section in one of the two arguments.