I found this macro in the priest macro wiki. I'ts an awesome tool. I've been using it for a lot of different things. can someone explain this macro in English? how would i adjust the distance for targeting things at or less than range 20?

/console targetNearestDistance #700
/targetenemy
/cast [nostance,nocombat,harm] Shadowform; [nostance,combat,harm] Shadow Word: Pain;[stance:1,harm] Shadow Word: Pain
/console targetNearestDistance #200