Dots or no dots from:

http://msdn2.microsoft.com/en-us/library/aa225964(SQL.80).aspx

The following text:

Note During a full database or differential backup, Microsoft® SQL Server™

backs up enough of the transaction log to produce a consistent database for when the database is restored.

Now I know the question is can a backup be started ... does not ask if it must be successful or even completed, but that is implied for why else would you do it.

So my question is: How does SQL backup a portion of the log file when the log file can not be backed up due to an open transaction.

Will somebody please explain.?