Abbreviations and acroyms are frquently used in business and technical writings. Abbreviateions are for of words and phrases that are shorter that the full form (e.g. Dr. is an abbreviated form of Doctor), while acronyms are words that are formed from the first letters of a group of words (e.g. WTO is an acronym of World Trade Organisation). Both abbreviations and acronyms are used in business writings because they have many advantages such as they occupy less space, save time, offer greater speed, ete. However there is no set rule as to the use of letters-capital or small and period after the letter. General rule is capitalize the abbreviated letters when they are used for the terms which are capitalized and put a period if you think that the abbreviation will otherwise create confusion.
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