It was a short way of writing a different spelling of the words all correct. Some foreign-born people wrote all correct as o-l-l k-o-r-r-e-c-t, and used the letters O.K.

VOA: special.2010.02.28

These between B and C and E and F didn't get filled in because they were already just the smallest amount that they wanted to deal with, just half steps.

但是B和C,E和F之间并没有被填上,因为它们之间已经是最小的距离,只是个半音级,人们愿意摆弄的最小距离

耶鲁公开课 - 聆听音乐课程节选

C E G Supposing we didn't go C,E,G, C E G C but we decided to start with the E,G and then put the C up on top,C,E,G,C.

如果说我们不按照这个顺序，而是按照E，G，然后将C音放到和弦的最上方。

耶鲁公开课 - 聆听音乐课程节选