Macintosh File System (MFS) is a filesystem used in early Macintosh models up to those running System 3, when the original HFS (which is supported within Linux) supported it. Although no Mac model that shipped or can run with an MFS-only macOS can run Linux, floppy disks formatted with an MFS system may still exist and the user never bothered to reformat it to HFS or HFS+, and the main use case I can think of is using MFS to transfer files from a modern device to a Mac that does not support HFS. It would be nice supporting the MFS filesystem natively within Linux, which could be read-only or read-write. MFS is a very limited filesystem, meaning it's simple to implement, albeit being less efficient than its successors. MFS stored files in a single flat structure without subdirectories; the illusion of "folders" was created by including a "directory handle" in each file entry so that the single directory could be scanned to find files that belong to a particular virtual folder. File names could be up to 255 characters, though Finder didn't support more than 63 or 31 characters (depending on the version). Resource Forks were introduced in MFS. An MFS volume consists of a boot block, a master directory block, some file directory blocks, and some allocation blocks. It may also have a backup master directory block, but this is optional. These blocks are each defined in terms of 512-byte sectors. Unless otherwise specified, all values are big-endian (MSB first). Information about the filesystem is relatively easy to find.
