BS A 314:1997

Aerospace. Nuts, hexagonal, plain, reduced height, normal across flats, with MJ threads, classifications: 450 MPa (at ambient temperature)/120 °C, 450 MPa (at ambient temperature)/235 °C, 600 MPa (at ambient temperature)/425 °C, 900 MPa (at ambient temperature)/235 °C, 900 MPa (at ambient temperature)/315 °C, 900 MPa (at ambient temperature)/650 °C, 1100 MPa (at ambient temperature)/235 °C, 1100