Hey Kris,

Good on you for digging into the Real Spellers archives. So much rich understanding to uncover.

I will just try to offer a few responses that might you get some traction to move your understanding a bit ahead -- and that of anyone else following along. Do make sure that you go back to the string and follow the link to the LEX post Gina mentioned on . That is key!

You write...

I know that a grapheme is generally defined as representing a phoneme, and that this is the reason for the question.

Indeed, graphemes are comprised of single letters, or two- or three-letter combinations that represent a phoneme. While we're add it, we can add some more details regarding graphemes including the following...

I highly recommend that readers explore the "Orthographic Phonology" album in the Real Spelling Gallery and study the film on the "phonological grapheme". 

You continue...

 But, does that mean that a grapheme cannot represent a null phoneme?  

An interesting question. I would be curious to hear what you mean by a "null phoneme". One thing that this excellent question highlights is the need to clarify our understanding of what a phoneme is. Again, I recommend going back to that "Orthographic Phonology" album in the Real Spelling Gallery, this time, study the film on "The English Phoneme". 

Knowing that there are actual linguists in the Real Spellers community who understand these linguistic concepts better than I, I'll share some of my understandings knowing that any impresisions I share will be refined by our colleagues...

One key point that took me some time to get my head around is the fact that phonemes are not actually "sounds". The are actually considered to be abstract concepts that can be represented by the range of pronunciations that speakers of a language perceive as the same phoneme. We can use the term "allophone" to describe the different pronunciations of the same phoneme. So if we compared my pronunciation of the word with someone with a Boston accent and someone with a Brittish accent we would each announce vowel phoneme very differently. But since we are English speakers we can understand eachother. In English those different pronunciations don't change the meaning of the word, so they are considered the same phoneme in English. We can say that those are all "allophones" of abstract Engilsh phoneme that can be represented with the IPA system this way /ɑɹ/. 

When you say "null phoneme" do you mean "zero pronunciation"? Because that's the terminology I'm used to. Here's an example of what I understand to be an example of a grapheme representing a range of pronunciatons that include "zero pronunciation".

If you say the word "print" you will feel the final /t/ phoneme represented by the grapheme. The tip of your tounge stops the air by touching the top of your mouth behind your teeth and then lets it out in a burst (a plosive). Now say the following phrase out loud:

"footprints in the snow"

When you said the word "footprints" your toungue never touched the top of your mouth when you pronounced the base <print>. If your tougue does not touch, it cannot stop the air, and therefore there is no "plosive" phoneme /t/. However, the grapheme is still written down, right there! 

My understanding is that we can still refer to the in the base as a grapheme becuase it does represent a phoneme. It is just that in this case it is an allophone that has "zero pronunciation". We English speakers still recognize the base even though there is no pronunciation of that /t/ phoneme. But we still write the grapheme! 

I know that is complex, and I fear that I'm expressing the edge of my understanding, so I will get some linguistic friends to check any impresisions I'm likely to be stating here. Again. Dive into the "orthographi phonology" Gallery, and even better the Orthographic Phonology disk in the Tool Box 2. 

You go on...

Particularly in this case, since it once represented a phoneme that has since changed.  I get it that it is now etymological in some words, but it is clearly related to the "ugh" that represents /f/.  So, I understand why it might not be considered a grapheme, but somehow that doesn't seem right either.

I think I have a sense of where you are going, but I'm not sure I can unpack this very well. 

I will say this, however.

By definition, graphemes represent phonemes -- including an allophone of zero pronunciation. But that doesn't mean that graphemes can't also carry etymological information. I know that is a grpaheme for /f/, but it also is almost always a sign of Greek origin. 

What is new to my understanding from studying with Gina and LEX is that for a letter or letter combination to be considered an etymological makrer in a word -- it cannot represent any pronunciation in that word -- or in any of its derviations. For example the in is an etymological marker, not a grapheme. Not only is this not associated with any pronunciation in the word 'two', that represents no pronunciation in any of the derivations of (e.g. twos, twofold). The is in this spelling simply to mark the link in meaning to words like twice, twenty, between, twin, etc. Note how this is different than the in . The is pronounced in some of the derivations of this base, but not in others. 

That is enough (too much!) for now. But I'll just hit post and see what happens next...