It's not at all like the "Da Vinci Code", but the combination of letters and numbers in a VIN code can be intriguing. An RV's Vehicle Identification Number (VIN) is a 17-character designation that appears near the bottom of the manufacturer's certification label. The law requires that this label be posted near the driver's door or to the left of the instrument panel in the cockpit of a motor home. In towable RVs it is placed on the left front exterior or near the hitch. You may see a manufacturer's coach identification number as well as a VIN. These two numbers must not be confused. Since manufacturers often outsource their motor home chassis, the year designation on the chassis VIN may not match the year on the motor home VIN.

Every model of every brand of RV has its own unique VIN, which is important to you as a consumer because it should appear on every piece of paperwork related to that RV from the time of its manufacture to its initial sale, warranty, repair work, accident records (if any), and subsequent sales, up to the time you decide to sell it yourself. It is especially critical when you are buying used to make certain that all paperwork you are shown matches the VIN on the actual RV.

Comparing VINs is easy once you are aware that you need to. Interpreting the information contained in the VIN presents some hurdles, however, since it's all in code.

• The first three characters in the VIN are the code for the RV manufacturer.
  
• The next five are the manufacturer's coded description of the vehicle, and include RV type, body type, length, and number of axles. To interpret those characters, you would need to contact the manufacturer.
  
• The next, or ninth, character is referred to as the "check digit". This is a calculation used to verify the VIN and is of no use to the consumer.
  
• Following that, the tenth character indicates the actual model year, with the years after 2000 shown as numbers. For example, 2001=1, 2002=2, etc. The years 1998-2000 have the letter designations W, X, and Y, with earlier models obviously going back through the alphabet (letters I, O,Q, and U are never used). After 2009, the designations will again revert to the letter code.
  
• The eleventh character is the code for the plant where the VIN was attached and must be obtained from the manufacturer.
  
• The remaining letters or numbers generally relate to the position of the RV in the production sequence and are also assigned by the manufacturer.

As you can see, most of the information "hidden" in the VIN can be obtained elsewhere. The manufacturer will be listed at the top of the certification label. The RV type is obvious. You can measure the RV yourself if there is any doubt about the length, and the number of axles is also obvious. Model year can be easily read from the label and should be compared with other sources of information.

For any number of reasons -- especially in legal situations, or if your RV is destroyed by fire -- you may need to know the location of the manufacturing plant and the RV's position in the production sequence. You can sometimes determine the sequence from the last six characters of the VIN. However, this coding is at the manufacturer's discretion -- which means you'll need to contact them for that information.

In the case of an RV built by a manufacturer who is no longer in business or if the label is missing or defaced, you'll have to do a little more digging. The N.A.D.A. RV Appraisal Guide lists brands going back as far as 1989 with the names and addresses of their original manufacturers. The older the RV, the more digging you may have to do.

To sum up, you need to be familiar with your RV's VIN so that you can compare the number on the vehicle with all paperwork relating to it and verify the model year. Most of the time, all you'll need is the full 17-character code and the tenth character, which is the model year code. Take what you need and leave the rest.

And that is how you can crack the VIN code ... don't tell Dan Brown.