Either Microsoft Programmers or Defaults.

In the CAST and CONVERT (TSQL) BOL article there is a table with formats. My date is returned as the following if Management Studio query window withput formatting:

2000-04-06 18:06:31.000

according to the table, the format name and description for that are:

ODBC canonical (with milliseconds)

yyyy-mm-dd hh:mi:ss.mmm(24h)

It is not just default:

Default mon dd yyyy hh:miAM (or PM)

My assumption that it may be a front end (Management Studio) programmers formatted it this way because of 2 things:

1. When I use Profiler to profile running a query in Management Studio, the Profiler shows the original query, so the formatting is done in the front end.

2. Linked Server to Oracle query returnes dates /times in the same format as when running a query towards SQL Server.