[QUOTE][i]Originally posted by m_d_marian [/i]
[B]So,
there are only one segment for an object.
[/B][/QUOTE]
Not necessarily so. A table (object) can have partitions (subobjects), and partitions are segments. So with partitioned tables and indexes you have more than one segment for table/index.

[QUOTE]
[B]
That means than an segment can be spread on multiple files? [/B][/QUOTE]
Yes.