The db-class where the selection must be defined

String defining the selection. It may specify directly (with no quote) any variable by its name (not its locator).

When this name is defined and the corresponding field already exists (selold is searched among the locators first, then among the variable names), this variable is reset as the current selection. This definition mode overrides all others.

Name given to the newly created selection variable, if defined.

When a selection already exists, the 'combine' keyword indicates how the current selection must be combined with the previous one. For more information on this keyword, see db.selcombine

When a selection already exists and a new selection is created, the previously existing selection is deleted beforehand if this flag is TRUE. Otherwise a new variable is created.