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

It's as if Milton places the beautiful poetry of Shakespeare into the mouth of this evil magician so as to dismiss all the more easily the easy, L'Allegro-mode of poetry that Shakespeare seems for Milton to embody.

这就好像弥尔顿把莎士比亚美丽的诗句,放进了邪恶魔术师的口中,所以可以更容易地反驳，好像莎士比亚把L’Allegro模式诗给弥尔顿去具体化。

耶鲁公开课 - 弥尔顿课程节选