noun
index hole (floppy disk)
Technical computing term referring to the small hole in a floppy disk used for sector positioning.
フロッピーディスクのインデックスホールが破損すると、データが読み取れなくなる。
If the index hole of a floppy disk is damaged, the data becomes unreadable.
Variant with interpunct; less common in modern usage.
Borrowed from English 'index hole'.