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2 Database Structure | 
3.1 General Rules to Follow GEOS provides a wide range of routines for working with databases. The routines all require that the calling thread have the VM file open. Most routines have to be passed the VMFileHandle of the appropriate VM file.
Almost all DB routines come in two forms. The standard form takes, among its arguments, the group-handle and the item-handle of an item to be affected. The other form is designed for use with "ungrouped" items. This form takes, as an argument, the item's
DBGroupAndItem
structure.
In addition to the routines listed here, all of the VM chain routines can work on DB items. Simply cast the
DBGroupAndItem
structure to type
VMChain
, and pass it in place of the chain argument(s). (
VMCopyVMChain()
will allocate the duplicate item as "ungrouped.") For more information about
VMChain
routines, see the VM chapter.
Setting and Using the Map Item
GEOS SDK TechDocs| | | 2 Database Structure | 3.1 General Rules to Follow