The termcap file supplied with IBM Informix 4GL contains entries for some function keys i.e. F1 - F10 but not others such as F11 and F12.
The F11 and F12 function keys do not work.
The reason certain function keys do not work is simply that they may not be defined in the $INFORMIXDIR/etc/termcap file for certain terminal emulation's.
This problem can occur regardless of platform or environment.
Diagnosing the problem
To determine what characters are being used for a specific function key, one can use the following Unix utility:
$ od -c
You can then hit a function key such as F11 and it will output the characters is expects for that specific key. For example, here are the outputs for F11 and F12:
$ od -c
The above correspond to \E23 and \E24 respectively in the termcap file.
Resolving the problem
To resolve the problem, simply backup your existing $INFORMIXDIR/etc/termcap file and add the following entries under the appropriate terminal emulation to enable both the F11 and F12 function keys: