MS Access to Oracle migration and german characters

In my registry it's GERMAN_GERMANY.WE8MSWIN1252. Do you mean this one?

o.k., meanwhile I read the NLS_LANG FAQ at

http://www.oracle.com/technology/tech/globalization/htdocs/nls_lang%20faq.htm#_Toc110410543

I also got this parameters for NLS_LANGUAGE
:
nls_database_parameters
NLS_LANGUAGE                   AMERICAN

nls_instance_parameters
NLS_LANGUAGE                   AMERICAN

nls_session_parameters
NLS_LANGUAGE                   GERMAN

And from nls_database_parameters
NLS_CHARACTERSET               AL32UTF8  

There is no variable set under sql*plus

I don't know wheter this information is important to solve the problem. If I understand the FAQ correctly AL32UTF8 should be able to hold characters from GERMAN_GERMANY.WE8MSWIN1252. And the session parameters should supersede the other ones. Or is this wrong?

Here is some more information. I run ms access 2000 exporter from sql developer with following options:
Export for Oracle SQL Developer
Export Table Data

At the end of the export process I got dat-files (like categories.dat) representing my tables and the containing data. In order to get the data in the database I generate data move scripts and run the so generated batch file.

Now the interesting thing: If I open these dat-files with windows editor all german characters are displayed properly. If I open the same file with wordpad the german characters are displayed as described in my first post.

Does anybody know a possible reason for this?