It's been a writing weekend, and I'm now thinking that if I consistently answered my clients' orthographic questions here instead of in an email just to them, I'd post here more often. So here goes.
I just finished teaching the Zero Allophone LEXinar. It's a class that really changes how we think about phonology when we consider its relationship with English orthography. While I don't plan to teach that class again for a while, I am teaching the Science of Silence LEXinar over the year-end break (December 28-31), which offers a more comprehensive look at graphemes that are not pronounced in specific English words.
One of my clients stayed up late Down Under to take this morning's final Zero Allophone installment in the wee Australian hours. She emailed me before going to bed in order to unload her thinking before attempting to sleep. "Would we ever refer to something like <kn> or <wh> as a marker because it reveals something about the words' etymology, previous pronunciation/spelling, etc?" she asked. "Or is marker reserved solely for unpronounc[ed] graphemes?"
So here's what I know about the subject.