Subject: SNA Service Transaction Names -Reply

From: Tom Miller <[email-masked]>
Date: Fri, 10 Feb 1995 17:45:04 -0700

John, 

One problem I see with your proposal is that the single quote (') is a valid
T61 character.  Because of this, with your proposal a standard TP with a
leading quote would be misinterpreted as a service TP.  Standard TPs
that start with a single quote but don't meet the criterial you've outlined
would be rejected in error.  Others that meet the criterial may be
interpreted incorectly as service TPs. 

We've had customers who have wanted to use service TPs with our
CPI-C implementation.  Since the CPI-C architecture left it open as to how
implementations were to handle this we came up with a scheme that
doesn't use a valid T61 character.  

The conventions for specifying a service TP name on CPI-C calls with the
Novell implementation  are

* Specify the name with from two to five bytes of ASCII characters.

* Specify the first byte of the name, for example, 0x23, with two bytes of
ASCII characters.

    --Split the first byte of the name into two nibbles, for example, 2 and 3,
and specify them in the low-order nibble of each ASCII byte.

    --Set the high-order nibble of each ASCII byte to 1, which indicates
that you are specifying a service TP name. Continuing with the example,
the first two bytes specified are 0x12 and 0x13.

*  Specify the remaining zero to three bytes of the name as ASCII
characters. For example, 007. 

Therefore, specify a service TP name of 0x23 007, as 0x12 0x13 007. 
The 007 will be converted to EBCDIC.  This scheme avoids the problem of
overlap between ASCII and EBCIDIC representations of valid T61
characters.  

Tom Miller
Novell, 408/747-4353