The MaxRemovablePartition field lets the end user control the number of drive letters that will be reserved for each removable media drive during system initialization.
If MaxRemovableDrivePartition entry is not present, the number of drive letters to be assigned will be based on the number of partitions on the media currently present at boot time. If no media is present at boot time then Windows 95 reserves 1 drive letter for each removable media.
Insertion of a media with partitions more than that defined by the MaxRemovableDrivePartition will result in a message that suggests to the user to increase MaxRemovablePartition. The message will also warn the user that some partitions on the media are not accessible in the current configuration.