x |= y

x = x | y

// cs_operator_or_assignment.cs
using System;
class MainClass
{
    static void Main() 
    {
        int a = 0x0c;
        a |= 0x06;
        Console.WriteLine("0x{0:x8}", a);
        bool b = true;
        b |= false;
        Console.WriteLine(b);
    }
}