Duan Yu was only able to absorb other people's internal energy via the placement of his thumb on the opponent. However, this limitation is due to Duan Yu not having mastered Beiming Shengong:
他的‘北冥神功’只练成一路‘手太阴肺经’,只有大拇指的少商穴和人相触,而对方又正在运劲,方能吸入内力 ,其余穴道却全不管用。
He has only learned one aspect of Beiming Shengong, which dictates that his thumb must make physical contact with the opponent, and the opponent must be generating internal energy, in order to absorb from the opponent.
Does this mean that Beiming Shengong possibly offers more flexible ways to absorb, and perhaps even AOETTA: Absorbing Of Energy Through The Air?