Numbers. Time of day

The content of these guidelines is taken from the third edition of the Vives University Network’s Interuniversity Style Guide for Writing Institutional Texts, an interuniversity project in which the UPC participates with the support of the Secretariat for Universities and Research of the Government of Catalonia.

Time of day

• Use numerals for times of day, but spell out the number with the expression o'clock, which is used to designate exact hours only.
  
  
• If you use the 12-hour clock, write a.m. and p.m. with points and a space between the time and the abbreviation. Use a point to separate hours from minutes.
  
  The lecture starts at 9.45 a.m.
  The library closes at 8 p.m.
  The secretary's office hours are from 8.30 a.m. till 2 p.m.
  The Rector's speech will begin at four o'clock.

• Spell out the number with the term o'clock, which is used to designate exact hours only.

• Use the terms noon (or 12 noon) and midnight, rather than 12 p.m. and 12 a.m.
  
  The tutorial, which was due to begin at noon, began at 1.15 p.m.
  The campus copy shop closes at 12 noon.
  The faculty bar will serve coffee until midnight.
  
  
• If you use the 24-hour clock, use a point to separate hours from minutes. Do not use the symbol h.
  
  The meeting is at 18.00.
  
  
• When using a.m. or p.m., avoid a leading zero.
  
  08.30 a.m.
  8.30 a.m.