The master dictionary (md) file contains commands, Procs, macros, menus, connectives, default attribute-defining items, and file-defining items [both local (D-pointers) and synonym (Q-pointers)].
The master dictionary is the root of the database table structure. By convention, the location of the master dictionary on the network is the location of the database, even though the tables in the database can be on another server.
There is one master dictionary file for each account. When a new account is created, a standard set of vocabulary items are copied into the new account’s master dictionary. File-defining items (D-pointers) and synonym-defining items (Q-pointers) are two types of file pointers found in a master dictionary. File-defining items point to files within the current account. Synonym-defining items can point to files either within the current account or within other accounts.