HP-UX SNAplus2 Upgrade Guide (August 2003)

Porting Application Programs
APPC
Chapter 336
APPC
If you are not making changes to the application's source code, no action
is necessary; the application can run unchanged with the new shared
libraries.
Recompiling Existing Appications
In SNAplus, the VCB field immediately following the opext field is
named reserv2 and is reserved. In Release 5, the opext field was
renamed format . The format field is used to distinguish between two
versions of a VCB.
When migrating applications from previous versions of SNAplus, no
source code changes are required because the SNAplus2 system
overwrites the application supplied value. However, it is recommended
that you explicitly set this field to zero for future compatibility.