Charles Ellicott Commentary Nehemiah 11:21

"But the Nethinim dwelt in Ophel: and Ziha and Gishpa were over the Nethinim." — Nehemiah 11:21 (ASV)

Ophel. —The Nethinims on the promontory of Ophel were either inside or outside the city, depending on whether the one wall or the other was taken. Here they are regarded as outside.