ring-sector

Also contains definitions of: atomic ring-sector, bond ring-sector
https://doi.org/10.1351/goldbook.R05398
A @ST06775@ of ring atoms, linked together as an unbranched chain and connecting two @B00736@ or junctions, but not itself containing any @B00736@ or junction, is termed an atomic ring-sector. A bond linking together directly two bridgeheads or junctions is termed a bond ring-sector.
Source:
Blue Book, p. 499 [Terms] [Book]