Post the whole command. Oracle's syntax is pretty rich and this excerpt doesn't look just right to me. You might also want to consult the documentation.
I'm sorry, I won't be able to help. It is giving syntax error to me (version 10g) and I can't find anything like it in the documentation, not even in 11g.
Are you absolutely sure this was successfully run on Oracle sometime? As far as I know, all Oracle features are documented, even those that are optional, and I don't see place for parenthesized numbers delimited by colon between the column name and data type in any of the syntax diagrams.