In some cases an object in the database is not described at all but is represented with an icon which has been predefined for this purpose. Unlike the case of bitmap drawings there are no standard formats for mapping databases that are used by the mapping vendors. Each one has an internal form that in proprietary and thus one database is designed to only work with one program. For this reason you will generally only use the database that was supplied with the program you bought. Some vendors change the format from year to year to you can only use maps supplied with that version of the program.
Some programs can use multiple databases but usually only from the same vendor.
In a few cases you may find that the form of the database is documented or just stored as easily interpreted text and you can alter or create your own database entries. Unfortunately because of the size and complications of the database, even when documented, most users would find this to be a formidable task. Even within a vendor the database format can change. For example the database format on the pc may be different from the way the information is stored once it is downloaded into the gps. The program performs a translation during the download.