usr/src/usr.bin/tn3270/api/README

apilib/

The files in this directory are not part of tn3270 proper.

They provide a C interface to the 3270 Applications Programming
Interface (API) provided by tn3270.

This interface is modeled after (and supposed to be compatible
with) the "low level" API provided with IBM's 3270 PC control
program version 3.  Note that we only provide a subset of the
API functionality.  This subset is (again supposed to be) consistent
with that subset provided by the IBM PC 3270 Emulation Program
version 3.00.  This subset is (somewhat sketchily) documented
in Volume 4, Number 4 of the IBM Personal Computer Proceedings.
The 3270 PC API itself is documented in SA23-0221 (I have revision
-01) "IBM 3270 Personal Computer Control Program -- Programming
Guide".

The INTENT is to allow the API from both MSDOS and from Unix.  Note,
however, that at the current time only MSDOS is supported.

Now, to program:

First, call "api_init()".  If it returns "1", then all is OK.  If
it returns "0", then the API is not active.

From then on, call whatever seems right.

You will need to include "../ctlr/oia.h" and "../api/api.h", at a
minimum.