Twin Cam production information (2111 cars) including option codes was hand copied from the factory production record books just prior to the factory closing and skipping all their records in 1981 by Phil Richer over several days. This information was then compiled into what ultimately became known as the "Yellow Book", which then has been refined and became the Dutch online database (Koen and Jerry).

In general, this option list may also apply to the "Deluxe" cars which share the Twin Cam chassis (except possibly the "Engine" option that may be unique to Twin Cam). Options for the "Deluxe" cars may also include a few things for the pushrod engines, like alloy valve cover for instance.

CODE	  NAME
455Ax	  4.556 rear Axle ratio -- perhaps 8% of all TC cars
4.875Ax	  4.875 rear Axle ratio -- so far only 2 recorded
Ae	  Aerial -- a few recorded, presume this is a stand-alone 
	  part when radio is NOT ordered)
AlSWh	  Alloy Special Wheel ? -- (none recorded so far), may be 
	  the very rare but well known pin drive aluminum wheels.
AnSh	  Andre Shock Absorber -- several of these recorded
ARBr	  Anti-Roll Bar -- only a few of these recorded, 
	  (apparently originally rare on Twin Cam, most TC were 1500
	  style with no mounting for the ARBr until June 1959)
AS	  Adjustable Steering (column) -- a couple dozen far, 
	  maybe only 1% of all TC cars (far below the average 
	  for other MGA)
ASWh	  Alloy Steering Wheel - about 6% to 7% of TC cars
AT	  Ash Tray -- over 100 recorded (about 5% of Twin Cams)
BB	  Badge Bar -- a couple dozen recorded
BC or
BATT.CVR  Individual Battery Covers -- several recorded
Bmpr	  Bumper -- one recorded as "less FtORdr&RrBmpr"
Bkt	  Bracket (fog lamp) -- only a couple recorded as "2FLtBkt"
CAP	  Unknown description -- couple dozen cases recorded, 
	  (anyone want to venture a guess?  perhaps same as COP?) 
CAV	  Cool Air Vent -- dozens recorded, about 2% of all TC, 
	  (a minority option in lieu of no heater)
CLtr	  Cigar Lighter -- about a dozen recorded (far less than AT)
COP	  Competition brake Pads -- at least one recorded
CRG	  Close Ratio Gears -- about 7% of all Twin Cam cars
CS or
Comp.STS  Competition Seats -- hundreds recorded, most popular 
	  accessory (after heater), about 35% of all TC
CScn	  Competition Windscreen -- about 8% of all TC, 
	  slightly more often than CRG
CT	  Centigrade Thermometer -- a few hundred recorded, 
	  about 8% of TC
Eng	  Engine -- a few hundred recorded (description not known), 
	  about 8% of TC.  This is NOT the notable 1762cc large
	  bore factory option (not generally known to the public).
FLt	  Fog Light - (mounting) -- dozens recorded, mostly "2FLt"
FshR	  Flash Relay -- only 1 recorded so far (oddly rare)
Ft	  Front (part of another code like SpFtShoc or FtORdr&RrBump)
FtSh	  Front Shock Absorbers -- one recorded as "SpFtShoc"
glTk	  (gallon) Fuel Tank -- one recorded as "15glTk"
GrLvr	  Gear Lever (description not known) -- none recorded so far
H	  Heater -- nearly 75% of all TC cars
HD	  Home Delivery -- Pick up in England, ship out of country
HT	  Hardtop -- exactly 5 recorded, from the factory,
	  these were on the 1959 Sebring TC race cars
Inst	  Instructions -- one recorded as "See Special Instructions"
LAST	  Light Alloy Steering Wheel -- none recorded so far, (may 
	  be similar to WSWh but different manufacturer, special)
LC	  Luggage Carrier -- a couple dozen recorded, about 1% 
	  of TC cars, one recorded as "LC.in boot"
LessBatt  Less Batteries -- about 3-1/2% recorded this way
Nuts	  Hub Nuts (not spinners) -- nearly 100 recorded so far, 
	  less than 5% of TC cars
OC	  Oil cooler -- hundreds of these recorded, perhaps 25% of 
	  all TC.  The TC oil cooler may be different from others, 
	  See OF-105C (engine)	
ORdr	  Overrider -- one recorded as "less FtORdr&RrBmpr"
RB	  Radiator Blind -- a couple dozen recorded (1% of TC cars)
RC	  Rev. Counter (description not known) -- none recorded so 
	  far, may not be applicable to MGA, as all MGA have a 
	  rev couter
Rcg       Racing -- (may be part of another extended option tag)
RcgTyres  Racing tyres -- at least 2 recorded as "RcgTyres"
Rr	  Rear (part of another extended option tag)
RS	  Road Speed ?
RSTyres	  Road Speed Tyres -- one recorded as "RSTyres", apparently 
	  these were more common later on 1600-MK-II "Deluxe" cars
RvLt	  Reverse Light-- one recorded (not popular for racing)
Sh	  Show (likely part of a longer code)
SHTyres	  Show Tyres  -- several recorded
SLt	  Spot Light -- at least one recorded
Sp	  Special (possibly requiring an attached description),
	  -- One recorded as "Special Covered Scuttle" 
SpBody	  Special Body -- one recorded
SpFtShoc  Special Front Shock absorbers -- one recorded
SSC	  Sliding Side Screen -- hundreds recorded, nearly 25% 
	  of all TC cars (in lieu of 1500 type)
SV	  Sun Visor -- less than 1% of all TC, about 1/3 recorded 
	  as "2Sv", presume for Coupe only
SWLTT	  Spare Wheel Less Tyre and Tube -- a few dozen recorded, 
	  about 2% of all TC cars
Tc	  Tonneau Cover -- hundreds recorded as "TCxx" where 
          xx is the colour code (most Twin Cam roadsters)
TcBk	  Tonneau cover, black -- hundreds recorded, about 25% of TC
TcBu	  Tonneau cover, blue
TH	  Twin Horns -- about 7% of all Tc cars
WM	  Wing Mirror -- a few dozen recorded "1WM", 
	  only a few with "2WM"
WSWh	  Wood-rim Steering Wheel -- several recorded
WT	  Radio -- dozens recorded, about 2-1/2% of all TC,
          Models = R5810-200R, R5818.230RA, R200TA/MG01, R230RA/N461, 
          R52T/M601, R500TA/M601,  R23088 R500TA
WUAe	  Wind-up Aerial -- (so far none recorded on TC cars)
WW	  Windscreen Washer -- hundreds of these recorded,
	  about 35% of all TC cars, some "1WW", a few "2WW"
WWT	  White Walled Tyres -- one recorded this way
Wwtyre	  White Walled Tyres -- A few recorded this way