A ZIP+4 code uses the basic 02119 Zip code plus four additional digits to identify a geographic segment within the five-digit delivery area, such as a Roxbury city block, a group of apartments, an individual high-volume receiver of mail or any other unit that could use an extra identifier to aid in efficient mail sorting and delivery in Massachusetts.
A proper noun is different from a pronoun. Days of the week are always capitalized and are proper nouns. Names of cities and names of people are proper nouns. Pronouns are words like he, she, it, you, yours. Yes, the days of the week are proper nouns and always capitalized. Pronouns are a class of words used to refer to other specific nouns. The most common English pronouns include he, she, it, me, I, us, we, you, they and them. If you capitalize it in the middle of a sentence, it's (generally) a proper noun.
I was always taught that proper nouns were the names of particular (i.e. specific one of kind items) persons, places, or things, and that all proper nouns should be capitalized. The names of the seasons certainly meet this criteria and I, for one, will, as I always have throughtout my 60 yr life, capitlaize them.