Could be either. Let’s apply the principle to your particular: is the “arbitrary” data functionally arbitrary or essential? if i’m sending 100 bitcoin to you, and it doesn’t matter to me whether the arbitrary data is empty, full of random data, a smiley face or frowny face, then the arbitrary data is accidental to the transaction, meaning it doesn’t matter what the arbitrary data is, the purpose of the transaction is monetary, to communicate value, and thus a monetary transaction. that’s actual “arbitrary” data, it doesn’t matter it’s the purpose, the final end of the transaction that determines its formal essence. that’s Aristotle if i’m sending 100 bitcoin to you in order to have access to the arbitrary data on the transaction and i won’t do the transaction unless the arbitrary data is exactly what i need it to be, it’s not “arbitrary” to the transaction, but its essence. if the “arbitrary” data matters to the transaction, that data is not arbitrary. you can do anything with a cucumber. we don’t pretend we don’t know the culinary difference between eating it and sitting on it. monetary and culinary are correlative in the metaphor. I don’t begrudge anyone for operating within the rules of the protocol. However, I think honestly speaking about what we are doing is key to the networks health. the protocol allows people to do non-monetary things right now, right wrong or indifferent. My point is that monetary vs non-monetary is not a mystery. I hope that makes sense.