example  shown  in  figure  5-2.  The  abbreviation “Ser”  precedes  the  serial  number  when  one  is used. If  a  “refer  to”  line  is  not  printed  on  the stationery, the identification symbols are placed at the right side of the page one line below the last line in the letterhead. The symbols are typed beginning  approximately  two  inches  from  the right side so that a one-inch margin is maintained. They  are  arranged  in  block  style  in  the  order described for symbols that follow a printed “refer to”  line. Dating the Letter The  date  is  typed  or  stamped  on  the  right  side of the page just below, and blocked with the last line  of  the  identification  symbols.  Correspondence is dated with the date on which it is signed. Special Postal Service If special postal service is used, the appropriate designation   (AIRMAIL,   REGISTERED   MAIL, CERTIFIED   MAIL,   or   SPECIAL   DELIVERY) is typed in capital letters or stamped at the left margin  on  the  fourth  line  below  the  last  line  of the  address  in  the  letterhead.  The  designation “REGISTERED  MAIL”  is  the  special  postal service  in  figure  5-2. “From”  Line The  use  of  a  “From”  line  is  optional  except when there is a specific need to include it. When a “From” line is used, it should include only that information, which together with the letterhead, will provide sufficient title and address for reply without  reference  documents  having  to  be consulted. This line identifies, by title, the official in  charge  of  the  component  of  the  Department of  the  Navy  originating  the  letter. The  “From”  line  is  typed  on  the  third  line below  the  designation  of  postal  service  in  an unclassified naval letter. It is placed on the seventh line below the last line of the letterhead address when there is no postal service designation. Two spaces  are  inserted  between  the  colon  after  the “From”   and   the   beginning   of   the   originator’s title. Titles  in  the  “From”  line  follow  the  forms shown in the Standard  Navy  Distribution  List, Catalog   of   Naval   Shore   Activities   (OPNAV 5-6 P09B2-105); the  Standard  Navy  Distribution  List, Operating   Forces   of   the   Navy,   Unified   and Specified   Commands,   U.S.   Elements   of International  Commands  (OPNAV   P09B2-107); and in the List of Marine Corps Activities (MCO P5400.6). “To”   Line Official   correspondence   intended   for   the incumbent  of  an  office,  and  pertaining  to  that office, is addressed to that individual by title and not  by  name.  The  title  is  written  in  the  same manner   as   on   the   “From”   line.   Sufficient information  is  given  to  ensure  that  the  letter  is delivered  expeditiously. The “To” line is placed on the line below the “From”  line.  If  there  is  no  “From”  line,  the “To”  line  is  placed  in  the  same  position  as  that prescribed  for  the  “From”  line  in  the  preceding section.  Four  spaces  are  inserted  between  the colon  after  the  “To”  and  the  beginning  of  the addressee’s title. “Via”  Line The use of a “Via” line is optional. It is used when it is necessary to have the letter endorsed by  one  or  more  addressees  before  it  is  received by  the  ultimate  addressee  indicated  in  the  “To” line. The “Via” line is placed on the line below the “To”  line.  When  there  is  more  than  one  “via” addressee,  each  one  is  numbered  with  Arabic numerals enclosed in parentheses. These numerals indicate   the   sequence   through   which   the correspondence  is  to  be  sent. “Subject” Line The abbreviation “Subj” is used to introduce a topical statement of the subject and nature of the correspondence. Only the first word and any proper  nouns  are  capitalized.  The  “Subj”  line  is typed on the second line below the last line of the “via”  entry,  or  of  the  “To”  entry  if  there  is  no “Via”  line. “Reference” Line A  “Reference”  line  is  an  optional  entry  on  a naval  letter.  The  abbreviation  “Ref”  is  used  to indicate that previously prepared material is being