It is considered untidy to mix abbreviations with full stops and ones without full stops in the same article. The first two examples below are both correct because the writer has been consistent.
Full Stops (Periods) in Abbreviations
- The band travelled around UK and USA last year.
- The band travelled around U.K. and U.S.A. last year.
- It was only shown on ITV and not B.B.C.
(This is an inconsistent use of full stops (periods). It is considered untidy.)
- The M.D. insisted that his PA had left by 4 o'clock.
The Tendency: Do Not Use Full Stops / Period in Uppercase Abbreviations but Use Them in Lowercase Abbreviations
Abbreviations made up of capital letters tend not to have full stops, but abbreviations made up of lowercase letters tend to have them. For example:
Note: This is a tendency not a rule.
(British Broadcasting Corporation)
(Linear Recursive Sequence)
(Columbia Broadcasting System)
(ante meridiem - before midday)
(post meridiem - after midday)
(id est - that is)
(exempli gratia - for the sake of an example)
(per procurationem - by the agency of)
If the abbreviation is a company name, copy whatever convention the company uses. For example:
Note: Do not worry about this point. There are very few companies who use full stops / periods in their names. I mean almost none.
- Our team was hosted by the Italian club A.S. Livorno Calcio.
(A.S. Livorno Calcio is the name shown on the logo and in all correspondence.)
- The shop will be taken over by the clothing company s.Oliver in June.
- We will meet at P.F. Chang's in Tokyo.
Do Not Use Two Full Stops / Periods If a Sentence Ends with an Abbreviation
If a sentence ends with an abbreviation (including a contraction like etc. ) that ends with a full stop / period, then do not use a full stop / period to show the end of the sentence. However, other end marks (such as question marks, exclamation marks) should be used. For example:
The only exception to doubling up end marks with full stops / periods is ellipsis (…). For example:
- I need milk, bread, cheese, etc.
- She moved from I.T.V. after an irresistible offer from the B.B.C.
- She moved from I.T.V. after an irresistible offer from the B.B.C..
(Logically, this is correct, but it is too unwieldy.)
- Will she move back to the B.B.C.?
(This is correct, but it looks a little scruffy. To avoid this, use BBC instead of B.B.C.)
- Standing tall and with the Lord's Prayer mumbling across our lips, we entered the chamber...."
(This ends in four dots: three for the ellipsis and one to end the sentence.)