Many times when there is hiring news for any government related job the question of Veteran's Preference comes up and there are usually questions regarding who rates it, how many points, and the different categories of Vet's Pref.
The following was recently put out by my union and describes the criteria used, by at least the FAA, in applying Veteran's Preference points towards competitive external announcements.

Quote:

Veterans’ Preference
Why Preference is Given

• Veterans' preference in its present form comes from the Veterans' Preference Act of 1944, as amended, and is now codified in various provisions of title 5, United States Code. By law, veterans who are disabled or who served on active duty in the Armed Forces during certain specified time periods or in military campaigns are entitled to preference over others in competitive external hiring.

When Preference Applies

• Preference in hiring applies to permanent and temporary positions when external competitive hiring procedures are used.
• To receive preference, a veteran must have been separated from active duty in the Armed Forces with an honorable or general discharge. As defined in 5 U.S.C. 2101(2), "Armed Forces" means the Army, Navy, Air Force, Marine Corps and Coast Guard. The veteran must also be eligible under one of the preference categories below.
• Military retirees at the rank of major, lieutenant commander, or higher are not eligible for preference in appointment unless they are disabled veterans. (This does not apply to Reservists who will not begin drawing military retired pay until age 60).
• For non-disabled users, active duty for training by National Guard or Reserve soldiers does not qualify as "active duty" for preference. For disabled veterans, active duty includes training service in the Reserves or National Guard, per the Merit Systems Protection Board decision in Hesse v. Department of the Army, 104 M.S.P.R. 647(2007). For purposes of these guidelines and 5 U.S.C. 2108, "war" means only those armed conflicts declared by congress as war.
• Eligible veterans should claim preference on their application or resume. Applicants claiming 10-point preference must complete Standard Form (SF-15), Application for 10-point Veteran Preference, and submit the requested documentation.

Preference Categories
The following preference categories and points are based on 5 U.S.C. 2108 and 3309 as modified by a length of service requirement in 38 U.S.C. 5303A(d). (The letters following each category, e.g., "CPS", "CP", "XP", "TP" are a short reference which will be used by the FAA in competitive external hiring procedures.)
5-point Preference (TP)

• Five points are added to the rating score of a veteran who served:
  • During a war; or
  • During the period April 28, 1952 through July 1, 1955; or
  • For more than 180 consecutive days, other than for training, any part of which occurred after January 31, 1955, and before October 15, 1976; or
  • During the Gulf War from August 2, 1990, through January 2, 1992; or
  • In a campaign or expedition for which a campaign medal has been authorized.
  • Any Armed Forces Expeditionary medal or campaign badge, including El Salvador, Lebanon, Grenada, Panama, Southwest Asia, Somalia, Haiti, and Bosnia qualifies for preference.
  • A Campaign medal holder or Gulf War veteran who originally enlisted after September 7, 1980, (or began active duty on or after October 14, 1982, and has not previously completed 24 months of continuous active duty) must have served continuously for 24 months or the full period called or ordered to active duty. The 24-month service requirement does not apply to 10-point preference eligibles separated for disability incurred or aggravated in the line of duty, or to veterans separated for hardship or other reasons under 10 U.S.C. 11 71 or 1173.

10-Point Compensable Disability Preference (CP)

• Ten points are added to the ranked numerical score of a veteran who served at any time and who has a compensable service-connected disability rating of at least 10 percent but less than 30 percent.

10-Point 30 Percent Compensable Disability Preference (CPS)

• Ten points are added to the ranked numerical score of a veteran who served at any time and who has a compensable service-connected disability rating of 30% percent.

10-Point Disability Preference (XP)

• Ten points are added to the ranked numerical score of a veteran who at any time has a present service-connected disability or is receiving compensation, disability retirement benefits, or pension from the military or the department of Veterans Affairs but does not qualify as a CP or CPS; or a veteran who received a Purple Heart.

10-Point Derived Preference (XP)

• Ten points area added to the numerical score of spouses, widows, widowers, or mothers of veterans. This type of preference is usually referred to a "Derived preference" because it is based on service of a veteran who is not able to use the preference. To receive 10-point preference (XP) the applicant must submit a SF-15 form and provide the required supporting documentation stipulated on the SF-15.

Hope this helps someone along the way.

USMCFLYR