首楞嚴義疏注經 2.463

2.463

水中可居曰洲，三千總號，閻浮中而復大者是此五天也，括結量數也。國，域也，有限域也。

Habitable land within water is called a continent (zhōu); three thousand is the collective designation; the one in the middle of Jambudvīpa that is even greater refers to the Five Indies; 'measuring' means calculating the numbers. 'State' (guó) means territory, having delimited boundaries.