From the Oracle on-line documentations, Oracle 9i Utilities, chapter 2. Please note snapshot = materialized view.
"The three interrelated objects in a snapshot system are the master table, optional snapshot log, and the snapshot itself. The tables (master table, snapshot log table definition, and snapshot tables) can be exported independently of one another. Snapshot logs can be exported only if you export the associated master table. You can export snapshots using full database or user-mode Export; you cannot use table-mode Export."
Yes, you are completely right also I it knew, that MVs are exported.
But I am interested, if during export, any of MV contained the data, these data also are taken by the Export utility, for consequent importation or the Export utility saves only definitions (DDL) of MV?
During export you have the option to include data. This is true for all tables, including tables used for materialized views. For example, at the command prompt you first issue the command "set ORACLE_SID=yoursid" and then you issue command "exp -help". It tells you you have the option to export rows or just definitions. The default value (Y) causes data to be exported. This is true for materialized view tables as well as regular tables.