Does format file for bulk insert allow mix of native and character format?

I tried to place this question to the .Net framework Data Access and Storage forum and got no answer, so I am trying to move it on this forum.

So I have a module which require me to import big amount of data. I believe that the native format data files with format files will be the most efficient way of implementation. I am trying to programmatically produce a BCP like exported files of native format(it means without type conversion) from tables with nullable and nonnullable values.I prefere to be able to not produce computed or identity or rowguid fields,so I need format files.

I don't have problems producing different kinds of int or float( which are the majority of fields) or char or nchar fields.

Problems are emerging with the datetime or smalldatetime or decimal fields because I don't know how to convert to them from the strings or from the CLR types.

So I trying to find a way to find a native format of those fields or to find if a bulk insert will accept mixed format files with some of the fields in the native format without field terminators and some with field terminators or to use char format with field terminators only plus maybe format files.

So if the answer to above question is positive I can partially resolve the problem, if negative I will have to use the character format.

Unless you can educate me on the convertion to the SQL server internal formats of datetimes and decimals from the CLR types.

See SQL Server 2005 Books Online topics:

SQL Server Data Types and Their .NET Framework Equivalents
http://msdn2.microsoft.com/en-us/library/ms131092.aspx
Specifying File Storage Type by Using bcp
http://msdn2.microsoft.com/en-US/library/ms189110.aspx

Data Type Conversion (Database Engine)
http://msdn2.microsoft.com/en-us/library/ms191530.aspx