/^\w+\s+(\d{3}|\w+)/

\w+ => "j30_98a3"
\s+ => "\n\n\t   \r"
\d{3} => "523"

(or)

\w+ => "j30_98a3"
\s+ => "\n\n\t   \r"
\w+ => "r4_QK4"