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abbreviations
The presentation of abbreviations in writing raises two questions:
■ Should I use full stops?
■ Do I use capital or small letters?
Full stops
■ Normally if you use initial (first) letters to represent words there is no need to put a full stop after them:
UK  BBC
■ In North America, however, it is more common to use a full stop (or ‘period’) after initial letters.
■ If the abbreviation consists of the first and last letters of the word, then you do not use a full stop:
Mr  Ltd
■ If the abbreviation consists of the first part of a word, you put a full stop at the end:
Wed.  Dec.
Capital or small letters
Normally if you use the first letter of a word in an abbreviation a capital letter is used:
HND  BAA  HSBC
One well-known exception to this rule is the abbreviation plc for public limited company, although this is also sometimes written PLC.
See also acronym.