all the information in this post is taken verbatim from
www.dvdplusrw.org
What are compatibility bitsettings?
For a DVD player or drive to identify what kind of disc is loaded, it queries some identifier info found in the lead-in section of each DVD disc. These few bits, commonly referred to as "compatibility bitsettings" tell the drive which specification the media conforms to, such as DVD-ROM (also used for normal DVD-Video discs), DVD+R or DVD+RW. Most DVD players will read a DVD+RW or DVD+R disc without any problems, however a small minority of them report a disc error when a disc is loaded that is not marked as a "DVD-ROM" disc in the compatibility bits.
When the manufacturer of a DVD-Video player or DVD-ROM drive that suffers from this problem does not provide a fix (for example by offering a firmware upgrade), you might try to "fool" the player into thinking that a DVD-ROM disc is loaded by changing the compatibility bits on the disc.
(taken from
http://www.dvdplusrw.org/Article.asp?mid=-1&aid=4 )
Compatiblity issues - Incorrect setting of compatibility bits
Some DVD players fail to read a DVD+R or DVD+RW disc when the "compatibility bits" at the lead-in section of a disc do not contain the value for DVD-ROM. Thankfully, there are ways to change these bitsettings using both a DVD+RW PC drive and a DVD+RW video recorder, which is explained in full detail in the article about bitsettings on this site. Players that are known to only read DVD+RW discs that need this procedure are marked in the compatibilitylist with (cs). However, it might be worth a try to apply this procedure to a disc when you have a player that is not listed as (cs), but you have troubles reading a disc. If you encounter reading problems with DVD+R discs, make sure that you apply DVD-ROM bitsettings on your DVD+R discs as well (Philips DVD video recorders, and some PC DVD+R drives such as the ones from HP will do this automatically - for others refer to the mentioned article).
(taken from
http://www.dvdplusrw.org/Article.asp?mid=-1&aid=46 )
Compatibility Bitsettings / Book Type Field
For a DVD player or drive to identify what kind of disc is loaded, it queries the so called "Book Type Field" found in the lead-in section of each DVD disc. These few bits, commonly referred to as "compatibility bitsettings" tell the drive which low-level format specification does the media conform to, such as DVD-ROM, DVD+R or DVD+RW.
Most DVD players will read a DVD+RW or DVD+R disc without any problems, however a small minority of them report a disc error when a disc is loaded that is not marked as a "DVD-ROM" disc in the compatibility bits. Ususally, these players are physically able to read the disc (since DVD+RW reflectivity is identical to that of a dual layered DVD-Video disc, which all players must be capable of reading), but their compatibility problems are due to different interpretations of these bits in the various firmware versions. In most cases, the problem can be solved by updating the firmware.
When a firmware fix is unavailable, or when you want to increase changes of playability when you give the disc to others with an unknown player, you could solve the issue by marking the DVD+R or DVD+RW disc as a DVD-ROM disc. This is what's called "changing the compatibility bitsettings". To instruct your DVD recorder to mark your DVD+R or DVD+RW discs as DVD-ROM, a special procedure must be followed. On a DVD+RW video recorder, you need to press a number of keys on the remote control. With a DVD+RW PC drive, you'll need a special utility program to accomplish this.
Note: You only need to apply this special compatibility setting to a disc if you encounter reading problems with your DVD equipment. Players and drives that need the DVD-ROM setting for DVD+RW discs are marked with (cs) in the compatibility list. DVD+RW drive vendors advice you not to apply these setting unless you specifically need so in your situation, however we think that no DVD drive or player should encounter problems with a disc marked as "DVD-ROM", as this is the default value for read only discs too.
On a DVD+R/+RW video recorder you can only change the bitsettings on a DVD+RW disc, after it has been recorded. DVD+R discs are recorded with the DVD-ROM identification, for highest compatibility.
Using a DVD+R/+RW PC drive, you can change the bitsettings on a DVD+RW disc, both on an already recorded DVD+RW disc, as well as by setting the drive to automatically write the desired identification by default on future DVD+RW or DVD+R discs. Since there is no way to change the identification bitsettings on a finalized DVD+R disc (as it is a write once), you can only set the drive to the desired bitsettings for new or unfinalized DVD+R discs.
(taken from
http://www.dvdplusrw.org/Article.asp?mid=0&aid=42 )
Apply compatibility bitsettings using a DVD+R/+RW video recorder
Apply compatibility bitsettings using a DVD+R/+RW PC drive
Command-line utility for changing the compatibility bitsetting
Bitsettings / Book Type Utilities download page
at the time of writing - only available for the following brands: Richo (and Richo-built), Lite-On, BenQ, HP, Nu, NEC.
