The native IRAF image format (known internally as OIF, or the original IRAF image format) has been modified in IRAF V2.11 to avoid file pathname length restrictions. In the process other improvements were made, and the new format is now machine independent and character data in the header is byte packed, allowing host programs to more easily be used to examine text data in image headers.
The old disk image format is still supported and is now referred to as OIF version 1 (V1). The new version introduced in IRAF V2.11 is OIF V2.
Images created with older versions of IRAF are still readable by V2.11. Images generated by V2.11 using the new format are not readable by earlier versions of IRAF. If it is necessary to generate images with V2.11 that are to be read by earlier versions of IRAF, the environment variable "oifversion" can be defined to force old format images to be written (but then there will still be pathname restrictions, etc.).
The good news is that now IRAF image headers support file path names up to 255 characters in length. Since the images are machine independent they can be shared by computers with different architectures, such as a Sun and a PC.
See an accompanying Newsletter article to read how this change affects images written using IMFORT.