In general, do not use periods between letters in abbreviations:
Right: John likes to use his PC on visits to Washington, DC.
No periods, no spaces:
BA—bachelor of arts
BFA—bachelor of fine arts
BS—bachelor of science
EdD—doctor of education
MS—master of science
PED—doctor of physical education
PhD—doctor of philosophy
Right: The lecturer is Jane Smith, PhD, associate professor of biology.
Use and apostrophe in bachelor's degree, a master's, etc., but there is no possessive in Bachelor of Arts or Master of Science, etc.
The word “degree” should not follow a degree abbreviation.
Right: He has a BA in foreign languages.
Wrong: He has a BA degree in foreign languages.
The word “degree” should not follow a full degree designation.
Right: He has a Bachelor of Arts in Foreign Languages.
Right: He has a bachelor’s in communication.
Wrong: He has a bachelor of arts degree in English.
Also see Capitalization
Never use the ampersand as a shortcut for “and.” Exceptions are proper names that use an ampersand as an official part of the name.
Wrong: Department of Recreation & Leisure Studies
Wrong: IDA201 Arts & Human Expression (course listing)
Right: Barnes & Noble
Right: Bausch & Lomb
Right: Office of Design & Production
No periods are needed (common usage):
Right: Her GPA is well above average.
The correct abbreviation is Rm., however, it also is correct to write out the entire word, Room. It is capitalized when it refers to a specific room.
Right: We’ve reserved Rm. 116
Right: The room we’ve reserved is 116.
Right: The program is being held in Room 116.
For a cleaner look (and fewer keystrokes), use postal abbreviations.
Right: The sophomore is from Jabberwocky, WV, the home of the brave.
Spell out names of states when they stand alone.
Right: Brockport students are eligible for New York state financial aid. (Please note that the word state is not capitalized, however, it is now acceptable to either use initial capital or initial lower case in New York State.) Departments of the United States are abbreviated US.
Right: US Department of Education
Lowercase when used as an adjective:
Right: The state of Maine is cold in the winter.
Right: I’m in a New York state of mind.
Uppercase when used as an adjective or is part of the formal name:
Right: The Village of Brockport has raised sewer taxes.
Wrong: The village of Brockport is on the US Historic Register.
Right: The New York State Thruway Authority collects tolls.
No periods are needed and use lower case.
No need for :00 for on the hour.
Use noon or midnight instead of 12 noon or 12 am.
Right: The Union is open 5 am – 11 pm
Right: The Union is open from 5 am to 11 pm.
Right: Lunch was served at noon.
Right: The concert ran 7 – 8:30 pm.
Mediterranean Passages: Religious, Linguistic, and Cultural
8:45 am - 7 pm
Writers Forum: Calvin Trillin