a symbolic problem in Bombieri–Vinogradov theorem

Question

I read this theorem in a paper written by James Maynard titled "small gaps between primes", and I ran into the symbol "$<<_ A$" and I don't know what it means. any help would be appreciated

Given $θ > 0,$ we say the primes have ‘level of distribution $θ$’ if, for any $A> 0$, we have $\sum_{q \le x^\theta} \max_{(a,q)=1}|π(x; q, a) − \frac{π(x)}{ϕ(q)}| <<_ A \frac{x}{(log x)^A}$ .

Answer 1

This just is a different way to express the big O notation. Some people write $g(x)=O(f(x))$ as $g(x)\ll f(x)$. This was, in fact, introduced by Vinogradov.