These two Hemingray CD 106s are both considered common. The only difference between them is that the insulator on the left has an underscore under the 'o' in No 9, the other does not. The insulator on the left has a full entry in the PC.....HEMINGRAY [100], there is no entry for the insulator on the right. It would seem to me given that these are both common insulators there could at least be a comment in the [100] listing that the insulator also occurs without the underscore. Something like {Note sometimes no underscore}