It should be noted that some Government agency  abbreviations  and  all  U.S.  Navy  rank abbreviations  are  written  without  periods.  For example: CIA  -  FBI  -  FHA  -  RADM  -  CAPT  -  LT Comma The comma is that mark of punctuation used in writing to indicate a slight pause or a separation of words, phrases, or clauses from other parts of the sentence that are not closely connected. It is the  most  frequently  used  mark  of  punctuation. Examples  of  various  uses  of  the  comma  are shown  below. To   separate   words,   phrases,   or   clauses used in a series in a sentence. This  is  an  accurate,  sturdy,  dependable compass.   (words) Guards are stationed inside the building, at  the  door,  and  at  the  gate.  (phrases) Senior Chief Taylor tried to do the work, but he did not have the right tools. (clauses of  a  compound  sentence). To  separate  nonrestrictive  clauses They  asked  Chief  Gibson,  who  was  the instructor,  to  explain  the  material. To  separate  an  adverbial  clause  at  the beginning  of  the  sentence. When Corporal Johns heard the alarm, he went to his post. To separate the name of a city, a state, or a  county. Houston,   Texas   -   Escambia   County, Florida NOTE: A comma should also be placed after the name of the state in a sentence when the city and state are used together. Houston,  Texas,  is  in  the  South. 5-24 To  separate  items  in  a  date. Monday,  October  26,  1942 NOTE: A comma should also be placed after the year in a sentence when the date and year are used together. On Monday, October 26, 1942, he started his  new  job. To   separate   an   appositive   (noun   or pronoun—often   with   modifiers—set   beside another  noun  or  pronoun  to  identify  it). Your  friend,  Bill,  is  the  coach. My  brother’s  car,  a  sporty  convertible,  is the  one  we  like  to  drive. To separate parenthetical expressions (side remarks  or  comments). Your  suggestion,  we  are  glad  to  say,  has been  adopted. To  set  off  yes,  no,  well,  etc.,  at  the beginning  of  a  sentence. Yes,  this  is  my  book. No,  Seaman  Jones  is  not  here. Well,  what  can  we  do? To set off persons addressed in a sentence. What  is  your  opinion,  Commander? I hope, my friend, that you have learned a lesson. Semicolon The  semicolon  and  the  comma  are  used  in much  the  same  way  in  a  sentence.  A  semicolon generally  serves  to  indicate  a  more  definite  break in a sentence than that indicated by the comma. Either  a  comma  or  a  semicolon  may  be  used  in compound  and  complex  sentences  to  separate clauses.  The  mark  used  is  determined  by  the meaning and how much of a break is required in the  sentence.  The  semicolon  provides  a  more