Attempting to OPEN a file with an invalid header.
A file was opened with MODE="CISAM" on a system that has intrinsic C-ISAM support, but the INFORMIX libraries are not installed.
Running PRO/5 Rev. 3 and opening a 4 GB file.
Running PRO/5 Rev. 2 and opening 64 bit file.
Running PRO/5 Rev. 2 (does not support 4 GB files) and opening a 4 GB file.