Manasara 6.23

6.23

tatsūtrāddakṣiṇe saumyaṃ tasya dvāraṃ prakalpayet
matsyapucchānane nyastaṃ sūtraṃ syāddakṣiṇottaram

from that cord to the south and north, he should construct its openings; / the cord placed across the tail and mouth of the fish-figure is the north-south line.