Symbol table and dictionary objects provide access to nongraphical objects (blocks, layers, linetypes, layouts, and so forth). Each drawing contains a set of nine fixed symbol tables, whereas the number of dictionaries in a drawing can vary based on the features and types of applications used in AutoCAD. New symbol tables cannot be added to a database.
A dictionary is a container object which can contain any AutoCAD object or an XRecord. Dictionaries are stored either in the database under the named object dictionary or as an extension dictionary of a table record or graphical entity. The named object dictionary is the master table for all of the dictionaries associated with a database. Unlike symbol tables, new dictionaries can be created and added to the named object dictionary.Dictionary objects cannot contain drawing entities.