pss
Enc: abbreviation for enclosure; addenda for business letter
There is only a 2 letter abbreviation of Quebec - QC.
The US Postal Service abbreviation is DE, though Del. is acceptable for use in text.DE is the standard abbreviation for Delaware
PS3
Addenda's
Proc. is the abbreviation for process.
The three-letter abbreviation for autumn is "AUT." This abbreviation is commonly used in various contexts, such as calendars and weather reports.
wyo.
CHO
ANG
The 3-letter abbreviation for the amino acid with sulfur in its molecule is Cys for Cysteine.
The plural form of addendum is addenda