I have been reading recently about Aristotle's "4 Causes" (Material, Formal, Efficient, and Final). Examples illustrate material as having to do with actual physical material. (E.g. the material cause of a table might be wood).
What is the corresponding material cause of something "virtual"? For example what is the material cause of a file on my computer? Is it the magnetic medium that the file resides upon? This doesn't seem correct as the file simply has no material. Does material cause even apply to a file?