Virtual Terminal questions

hello all,

sorry this is not a MI specific question, but i think 5250 datastream knowledge 
is in this place.

i am writing a virtual terminal client pgm. It redirects datastream to the 
workstation of the client job using USRDFN DDS, and must be totaly tranparent. 
I took an example from Bruce Vining as base (did just a few change for the 
moment). The example can be found here:

http://groups.google.fr/groups?q=virtual+terminal+group:comp.sys.ibm.as400.misc&hl=fr&lr=&ie=UTF-8&selm=19970508162310.400MISC_.NETNEWS_.globenet%40ibm.c


system request and attention keys are triggered by exit points: no problem, and 
i don't want to loose time for test request key.

now i don't know how to do some things:
1) trigger the help in error state
    i want my program to process the help key in this state, because currently 
when the error is a keyboard error like KBD0005 of QCPFMSG, it gives access to 
the job log of the CLIENT job, a bad thing, and because when the message is the 
result of a DDS COMP, RANGE, VALUES, etc... keyword, it gives CPF5239 (no help 
available): another help in error state.

2) trigger IO errors
    i can know when a IO error occured, just watching status in INFDS, but i 
don't know how to retrieve the SNA response code. In fact, i can get it using 
RCVMSG, but i wonder if there is a more direct way.

3) get qualified name of the 'server' job
    i use USER=*CURRENT PASSWORD=*NONE when opening virtual terminal, so if 
it's succesful, i'm always signed on and so have a job behind. Is there a way 
to know from which job comes the datastream (considering TFRSECJOB). At this 
time i force workstation name to 'VRTERM000S' when current wrkstn is 
'QPADEV000S' and plan to use QUSLJOB or something like that.

4) avoid infinite VT chains
    my program is meant to be automatically called by each interactive job, but 
it must not open a VT if already 'virtual'. Is there a way to know if it is, 
and who is the client.

thanks in advance.
Nicolas