Literacy is a particular interest of mine, and I have never heard of this. I would recommend deletion.
This seems to be an odd way of thinking for someone helping to write an encyclopedia: I’m an expert; I’ve never heard of this; this, therefore, cannot exist.
One truth that I am continually confronted with (especially when I visit Wikipedia) is that there are more things that exist than I have heard of. This is especially true in the areas in which I consider myself an expert.