[2019] Dungeoneering Abbreviations help

hey so I'm an on and off player since 2003 and since the early days of dungeoneering the abbreviations have changed, like i see for example nowadays I see W+3 or A+4 and i have no idea what that means. I want to join teams like I used to years ago but dont want to annoy people by trying to join parties that I dont meet the requirements for, please help me understand