SQLNet vs Two-task link problems

I am running Oracle 7.0.16 on a DEC Alpha under OpenVMS 6.1.

I have SQLNet installed, and it works fine (meaning I can connect using SQLPlus, see my tables, etc).

Now... here's the dilemma. I have a ProFORTRAN application, which I linked WITHOUT the two-task option (the "T" flag on the LNPROFOR command). When I run it on the server, it works fine. It connects to my database.

Now... I want to be able to run that same application on remote client machines. So... I linked WITH the two-task option. Lo and behold, it will not connect to Oracle, even when I run it on the server machine. The oracle username/password I use is the same in both cases (XDI/XDI_at_SCOTTY, if you want to know). SCOTTY is defined in the TNSNAMES.ORA file, etc. And I can connect using SQLPlus using this exact same username and password.

By the way, I have linked this exact same application at other sites running Oracle 7.0.16 and it works fine, which leads me to conclude that something about Oracle at my site is simply not configured right.

I get an ORA-06400, which is a SQLNet error, when my application tries to CONNECT.

Question 1: What on Earth has the two-task link option got to do with

            SQLNet?  I thought the two-task option just linked without
            the sharable image (i.e., it pulls the library references
            right into the final executable .EXE file so that it
            is portable and can run without the sharable image being
            installed).
Question 2: I called Oracle support (why I bother, I will never know).
            They said that ORA-06400 is a SQLNet version 1 error.
            But I am not  using version 1.  I don't even have
            the version 1 drivers built on my machine.  Is this really
            a version 1 error?
Question 3: Oracle support told me that 6400 means I have no default host 
            string defined, but they couldn't tell what I should set it to.
            Why do I need one?  I told it XDI/XDI_at_SCOTTY.  Doesn't it
            just look up "SCOTTY" in my TNSNAMES.ORA file?  It's defined
            in there, with  the nodename, the protocol (DECNET), the
            SID, etc.  I tried defining ORA_DFLT_HOSTSTR as "2:", but
            that didn't help.
Question 4: While we are on the subject, what is the syntax and allowable
            values for ORA_DFLT_HOSTSTR?  I have asked three (count 'em, 3!)
            different technical support people at Oracle what these
            values mean and the only answer I have ever gotten is,
            "I dunno, but '2:' is what makes it work."  
Question 5: My LISTENER.ORA file specifies the file SRV2.COM as the
            command file to run for incoming connection requests.
            In SRV2.COM, at the end, I have the line:
                  orasrv "(LOCAL=NO)"

            It was: orasrv "2:"
            that's how it came from Oracle, but it never worked that
            way at all (not even from SQLPlus) and Oracle Support
            told me to change it to "(LOCAL=NO)"  They could not tell me
            why.

            What does "2:" mean?  What does "(LOCAL=NO)" mean?  The
            orasrv image takes, I think, about 8 command line arguments.
            Is this documented anywhere?  What are the arguments, what
            are their allowable values?  etc?  I have never been able to
            find this in any of the manuals and I have yet to find
            anyone at Oracle support who can tell me this.

Thank you to the brave soul who can help answer any of my questions.

-- 
Max Magliaro
MMM_at_ICF.HRB.COM
Philipsburg, Pennsylvania

"I'm sorry, I can't find out what your CSI number is, we don't
 keep that in our database." 

           --- Worldwide Oracle Support