title: Pull value from specified place in URL using Regex
body: <p>I am brand new to regex and need some assistance in how to write an expression to pull the value after the third _ and fourth _ within my URL:</p>
  
  <p><a href="http://www.companyA.com?scid=sm_aw_ban_PQRSTUV_OP12561" rel="nofollow">http://www.companyA.com?scid=sm_aw_ban_PQRSTUV_OP12561</a></p>
  
  <p>I just want to find "PQRSTUV" (which will be different for every URL), and then using a separate regex find the value "OP12561" (which will also be different for every URL)</p>