The size of the mini-FSD file image plus the RIPL data area may not exceed 62K. In addition, the memory requirements of the mini-FSD may not exceed 64K.

The mini-FSD is only required to support reading of a file. Therefore, any call to DosWrite (or other non-supported functions) which becomes redirected to the mini-FSD may be rejected. For this reason, it is required that the IFS= command which loads the FSD which will replace the mini-FSD be the first IFS= command in CONFIG.SYS. Also, only DEVICE= commands which load device drivers required by that FSD should appear before the first IFS= command.

If the mini-FSD needs to switch to real mode, it must use the MFSH_CALLRM function. This is required to keep OS/2 informed of the mode switching.

Each FSD which is bootable is required to provide their "black box" to load OS2LDR and the mini-FSD into memory before OS2LDR is given control.

Additionally, these FSDs are required to provide a single executable module in order to support the OS/2 SYS utility. The executable provided will be invoked by this utility when performing a SYS for that file system. The command line that was passed to the utility will be passed unchanged to the executable.

The supplied executable must do whatever is required to make the partition bootable. At the very least, it must install a boot sector. It also needs to install the "black box", mini-FSD, OS2LDR and OS2KRNL.