# Is there a name for X when X bitwise OR Y is Y?

I'm wondering if there is a mathematical or computer science term for a number X such that Y | X = Y? For example:

66536 | 1000 == 66536


In this case, 1000 is the "insert name here" of 66536. Perhaps there is no name for this..? I've tried searching for "bitwise OR returns itself" and other such terms but without luck so far.

• For single bit variables $x,y$ we have $x\lor y=y$ iff $x\le y$. So perhaps "bitwise less-or-equal"? Aug 4 '20 at 20:04
• I don't think there is one. Similarly to en.wikipedia.org/wiki/Identity_element, I would call it "neutral element for $Y$"
– user114966
Aug 4 '20 at 20:18

I would say that $$X$$ is a subset of $$Y$$, in terms of bits set.