Distinct molecules called agglutinogens (a type of antigen) are attached to the surface of red blood cells. There are two different types of agglutinogens, type A and type B. Each type has different properties.
MDB: Geodatabase. The geodatabase is a collection of geographic datasets of various types, with the most basic types being vector, raster, and tabular data. There are three types of geodatabases: file, personal, and ArcSDE. Geodatabases are the native data format for ESRI's ArcGIS.
See SQL reference for query expressions used in ArcGIS for information on subqueries. In most ArcGIS dialog boxes where you build a query expression, the name of the layer or table is supplied for you (or you select it from a drop-down list).