This makes a lot more sense to me. And in thinking about it overnight, I know that I have seen tags that read both flax and linen. It seems odd to me that the two would be interchangeable on a composition tag. Plus, to your point, Derek, flax is the precursor to linen.
So I guess my question still stands. Worse comes to worst I'll likely go back to the quest for a suitable wool/linen(/silk/cashmere) blend, but I was really intrigued by the idea of a crunchier, lightweight, casual fabric to pair with jeans or chinos.