It all depends on the manufacturer of the plug as the marking are unique to them. Here is a link to the table for NGK plugs: http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqcode.asp?mode=nml
If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.If you mean single Roman letters, they can either stand for numbers or abbreviations.
The unknowns or variables
ID1232132123's answer is: Albert Champion Doug's answer is: Alternating Current
the R stands for Resistor. It is a resistor plug.
Go to the following site (Champion) with the link supplied and at he bottom of the page look at "Manufacturers numbering system" for an explaination. http://www.championsparkplugs.com/sparkplug411.asp
if your talking about the vin, they represent a variety of things about the vehicle.
Remove the spark plugs, dump in some 2 cycle oil over each piston, replace the spark plugs, turn the engine over 1 or 2 times, Let the Jet Ski stand for a while.
AC stands for Albert Champion, the founder of the AC Spark Plug Company. So, next time you're cruising down the road, just remember you've got good ol' Albert Champion to thank for keeping your engine firing on all cylinders.
X V D C in roman numerals
Variables are letters that stand for numbers x=5 y=3 j=4 J+X = 9
The passenger side spark plugs are accessed by removing the R/F tire and inner fender well. Make sure to place vehicle on a (jack stand, in park, chock the rear tire) and not just the jack. With the inner fender liner removed, you will be able to see the spark plugs. Gap is .052-.056" 13lb-ft of torque.
The letters stand for the German Quotient and Zahlen.