The naval use of the letter "X", used singularly or in combination with other letters, leading to a revisit to one of the examples for a more detailed explanation.

Here are just twenty six "events" which include the letter "X" in some form or other, which were in common use in my time in the navy.  You may be able to think of more, but the point is made.  The letter "X" figured in some large measure when compared with other letters of the alphabet whether vowels or consonants.

1. X for being  'wrong' [or incorrect] in written examinations
2. X for 'kiss' 'x' in letters from/to home
3. X for 'factor', leading to extra pay for "service hardships".
4. X for Startex, Comex, Finex, Endex, meaning, for example, Commence Exercise, Finish Exercise etc
5. X for the large gun 'turret' aft [one of two] on a large warship manned by the RMA [Royal Marines Artillery]. The other is called 'Y' turret, manned by bluejackets, and sits further aft than 'X' turret.
6. X for 'x openings' in NBCD States of a warship. Basically, the warship cruises in a relaxed state with watertight doors and scuttles [port holes] open, a State called 'X'. When it is likely that the ship will enter dangerous waters, the state changes to great awareness and doors and scuttles are tightly controlled: this is State 'Y'. When the enemy is sighted a State of  'Z' occurs and all openings are RIGIDLY controlled by ALL personnel. For the purists among you, please, no emails pointing out my errors [which are intentional] keeping the concept easy to follow. NBCD stands for Nuclear Biological Chemical Defence which protects those inside the ship from nuclear fall-out and gas attacks
7. X for NBCDX, GUNEX, NAVCOMEX etc with an 'e' or without. "NBCD [already defined] X" means exercising those procedures to keep the ship safe. GUNEX is a gunnery exercise either against aircraft, surface ships or shore targets. NAVCOMEX  is a Naval Communications Exercise testing personal skills of sending and receiving messages
8. X for XO - the ship's Executive Officer - a Commander in large vessel/establishment, otherwise No1 or first lieutenant.  He is second in command
9. X for 'X' as a prefix in naval ratings official service numbers until the 1st April 1953. It was introduced after the Invergordon mutiny and reflected inferior pay for new recruits, whereas, those already in the navy stayed on their current pre mutiny pay and didn't have the imposition of having the prefix
10. X for Exped, which is short for 'Expedition Training', where naval teams would go out an about and develop themselves, usually undertaking orientating tasks. Whatever, fun, leadership and participation were the qualifying requirements
11. X for RNXS, meaning Royal Naval Auxiliary Service. It was formed in 1963 and disbanded in 1994 because of defence cuts. They were tasked to  protected ports from nuclear attacks
12. X for a Type 'X' cryptographic machine - allied equivalent to the German Enigma Machine. It was used by the British and the Americans [a US invention] but after WW2, the British added an additional unit to the original machine, divorcing the codes it employed from those used by the Americans in continuation.
13. X for 'X' Craft miniature British submarines whose brave sailors were famed for their exploits against the German's, Italians and Japanese, receiving several VC's
14. X for TX, to transmit, and TX, time expired when one leaves the navy for pension for example
15. X for RX meaning to receive
16. X for PAX [Britannia] - peace of, or for, Britian
17. X for FX meaning the Forecastle of a warship
18. X for AX meaning the  Aftercastle of a warship, [Quarterdeck], which is on the after part of the ship, given over for ceremonial  and officers recreation when not in action
19. X for LX meaning a  Radio private greetings telegram sent from a ship [warship or merchant ship] to a UK address
20. X for PX meaning a  USN canteen/shop, occasionally frequented by British sailors when abroad
21. X for WX meaning Weather
22. X  for XX meaning a  DATUM POINT used in several situations
23. X for COMBRAX meaning  Commodore [Naval] Barracks. The senior officer of a ports main naval barracks which has a large number of men, many of them itinerant
24. X for X - local mean time [LMT] zone when sailing in waters of longitude 150 to 160 degrees WEST [approx]. In the UK, we keep 'A' time in summer and 'Z' time in winter as our LMT.
25. X  for X Rations - an army ration pack of pre cooked wholesome foods issued before a battle from 1944 onwards, and often given to royal marines [embarked] and to the navy particularly to submariners
26. X for X Section - a user trials section officially known as URTS [User Requirements Trials Section] generally interfacing a School/Fleet Branch with a design/manufacturer/fit-out authority, for example, the Signal School {HMS Mercury} with ASWE [Admiralty Surface Weapons Establishment at Portsmouth] and the Torpedo Anti Submarine School [HMS Vernon] with AUWE [Admiralty Under Water Establishment at Portland]

As mentioned above, one of these 26 subjects is worthy of further explanation and that is number 3, the X FACTOR, the military/naval one, and not the British so called Talent Show. However, in a perverse way, the winner[s] of the television talent shows go on to win some fame and extra money for they are deemed to have something special over and above other ambitious make-e-learnee entertainers, in the same way that members of the armed forces are special for the commitment they make to the country over and above ALL civilians. Thus they deserve recognition and rewards.

 Back in 1967/8, the powers that were, decided that the armed forces should be paid a going rate for their training, employment and expertise. The going rate had to have a datum, and the datum used was to be a comparison with civilians and the wages/salaries they were earning. A team of 'experts', gathered from civilian and military sources, formed a committee who reported that the way ahead was not the willy-nilly  armed forces pay, as had always been the case, where, amongst other anomalies, married men were paid more than single men, but a clearly defined Military Salary with direct comparisons with civilian jobs, training and responsibilities. That Committee report was accepted and introduced, which brought a nice little pay hike to men and women of the Royal Navy and WRNS commencing on the 1st April 1970

However, civilians were not forced to leave home for appointments/drafts abroad [ashore or at sea] nor did they have to put up with privations, less than adequate accommodation and often poor food, and ultimately, they were not shot at as they walked from the Saturday afternoon football match to the night club with lovely girls aplenty and stocks of booze which could be replenished at the drop of the hat. Oh, and of course the mandatory Sunday morning lie-in before rising to go to the club for a few more wets before Sunday lunch followed by the mandatory three hour snooze! Thereafter, an almost forced march [by friends] to the Sunday night thrash only to rise Monday morning to spend all day at work in a drunken stupor, disinterested, unproductive and a drag on the finances of tolerant employers.

Since the average sailor could not and did not do this, there had to be some form of compensation for the denial of privileges enjoyed by civilians. This same committee, then decided that another hike in pay should reflect the disadvantages of being in the armed forces, which was readily accepted by the Ministry of Defence. It was known as the "X FACTOR" and although not over generous, was seen as realistic and gratefully received by men of the armed forces.  Women, WNRS, WRACS and WRAFS were not treated as generously but were awarded their own level of X FACTOR. The X FACTOR took into account :-

1.  Exposure to danger
2.  Discipline
3.  Total commitment to the Service and the frequent uprooting that is inseparable from Service Life.

Anyone of these features could be found in some civilian employments but not the same combinations. Some leading civilians dared to call into question the exciting life we had in the navy, the wonderful travel we had with breakfast served in our hammocks by the duty CPO and evening drinks on the quarterdeck by the DLC [Duty Lieutenant Commander] not to mention that we had jobs for life, even though many were doing their best to get the hell out of the services. I believe that the admirals, generals and air chief marshals were polite in negotiation, but cocked a snook at those wanting to water down the new status gained by the armed forces,  awarding a 5% of basic pay for the new additional X FACTOR whilst at the same time, considerably raising the specialist allowances of submarine, flying, diving and parachute pay and retaining KUA and hard layers pay.  Many other perks followed and more importantly, the promise of regular annual updates was kept.  With all the allowances when serving in boats, BSA [Boarding School Allowance], S/M Pay, Hard Layers, Separation Allowance, X FACTOR, enhanced basic pay, extra travel warrants etc, we submariners were very well off but it came at a price with the amount of sea time we had to put in as a cold-war dividend..

Good sailing.