How would you write mathematically that a random variable follows some unknown distribution? For example, if I had a random variable X and knew it followed a normal distribution, I might write:
$X \sim N(5, 10)$
What would I write if I'm trying to say that the distribution is unknown?
$X \in \Omega$
Is that correct? It doesn't feel right.

The notation I tend to see is something like $X\sim F_X$ to denote that $X$ is a random variable with $F_X$ as its CDF. I have seen people try to be brief and just write $X\sim F$, but this could mislead others into thinking that $X$ has an $F$ distribution, when that could be far from the case.
