Some info on Phase One IIQ formats:
"IIQ RAW S and IIQ RAW L
Phase One digital back users can choose between storing their tethered captures in two different types of compressed RAW files.
IIQ RAW stands for Intelligent Image Quality RAW. It is an intelligent way of turning the full 16 bit image data captured by the camera into a compact RAW file format.
The IIQ Large RAW format is unique because it is completely lossless. IIQ RAW Large can be processed into a 16 bit TIFF, even though it is only half the size of a traditional RAW file.
The IIQ RAW Small format is based on the full 16 bit data that is captured by the digital back’s CCD. However, unlike IIQ RAW Large, it is not 100% lossless. Most users will not notice any quality difference between the two file formats especially if the IIQ RAW Small format capture is well exposed and set on a low ISO rating"
For example I just checked out some shots I did recently with the IQ180 and the IIQL files were between 72 and 80 MB while the IIQS files were 42 and 48MB.
Lance