Glossary for Geospatial Science

vector units:  The units in which vector coordinates and vector object extent are expressed.  These units are specific to individual vector objects and are dependent on how the vector was created.  The unit size may be a screen pixel and the object extents the same as the drawing area in pixels if the vector object was drawn without a reference object.  The unit size is related to the number of raster cells if the vector is created using an ungeoreferenced raster for reference; the object extents equal the number of raster cells times the cell size.  The units correspond to geographic coordinates and the object extents correspond to the geographic extents if the vector is created over a georeferenced object.