Serving area

A really dumb question..but i can't find the answer.

When serving in Doubles i know you use the shorter back line, unlike singles, but am confused as to the width - is it the very outside line as in general play in doubles or do you still have to get it in the narrower line like singles.

i really don't know the answer to this question and a two second response from someone would really help.

Thanks

 

thank you !
you wouldn't believe we've been playing for two years!