MDAC 2.5 SDK - ODBC Programmer's Reference
Chapter 11: Retrieving Results (Advanced)
A bookmark is a value used to identify a row of data. The meaning of the bookmark value is known only to the driver or data source. For example, it might be as simple as a row number or as complex as a disk address. Bookmarks in ODBC are a bit different from bookmarks in real books. In a real book, the reader places a bookmark at a specific page and then looks for that bookmark to return to the page. In ODBC, the application requests a bookmark for a particular row, stores it, and passes it back to the cursor to return to the row. Thus, bookmarks in ODBC are similar to a reader writing down a page number, remembering it, and then looking up the page again.
To determine a driver's support of bookmarks, an application calls SQLGetInfo with the SQL_BOOKMARK_PERSISTENCE option. The bits in this value describe what operations bookmarks survive, such as whether bookmarks are still valid after the cursor is closed.