dbs/db4/driver_type is a SAP Parameter attribute which is used to control Database driver type used by DBSL information. This is available within R/3 SAP systems depending on the version and release level.
Below is the standard documentation available and a few details of the attributes values .
Choose the database driver (XDN or XDA). For more information, see SAP
Note 1257635.
The currently active driver is visible in the developer trace (SM50),
for example:
See SAP Parameter Documentation for full SAP documentation for this profile parameter.