Uniface DBMS driver calls log ($ioprint 2-63)

I am doing some Uniface application tuning and after raising $ioprint value I can collect more information on all DBMS driver calls done by Uniface runtime. Here it is an example:

Server: I/O function: S, mode: 0, on file/table: COSERV index: 1 >=

I never fixed my attention on latest characters in these rows, those after "index: X".
Going through my complete log I find these combinations:
=
>=
<
but I could suppose others combinations should be in use too, like:
<=
>
and could be others.

I've looked into documentation but without luck.

Which is the exact meaning of latest characters after "index: x" in driver calls log row?
Are they index hints, like "index: X", sent from runtime to DBMS driver?

Thanks in advance for any answer!
Gianni