A0, A-0, A<sub>0</sub>, or a<sub>0</sub> may refer to:

  • 101 A0 and 103 A0, two versions of the German Heinkel Tourist moped
  • A0 paper size, an international ISO 216 standard paper size (841 × 1189&nbsp;mm), which results in an area very close to 1 m<sup>2</sup>
  • A0 highway (Zimbabwe), a highway which orbits Zimbabwe
  • A0, the lowest A (musical note) note on a standard piano
  • A0, a climbing grade
  • A00, Irregular chess openings code in the Encyclopaedia of Chess Openings
  • A00, an unofficial paper size twice the size of A0 paper size
  • A-0 Geyser, a geyser in Yellowstone National Park
  • A-0 System, an early compiler-related tool developed for electronic computers
  • L'Avion, IATA airline designator for the French airline
  • Characters of type A<sub>0</sub>, an older term for algebraic Hecke characters
  • a<sub>0</sub>, the accepted mathematical symbol for the Bohr radius
  • Haplogroup A00 and A0; see Y-chromosomal Adam and Haplogroup A (Y-DNA)
  • A0, a subdivision in stellar classification
  • A0, sometimes written as 0xA0, is the hexadecimal representation of non-breaking space in various character encoding standards
  • A0 road (Sri Lanka), an A-Grade road in Sri Lanka
  • Bucharest Ring Motorway, The Bucharest Ring Motorway, termed A0

Airplanes and rockets

  • A-0, a 1943 Pre-production model of the German Walter HWK 509 liquid-fuel bipropellant rocket engine
  • A-0, a 1938 variant of the German Siebel Si 204 transport and trainer aircraft
  • He 177 A-0, a pre-production series of the 1942 German Heinkel He 177 heavy bomber
  • Hs 126A-0, a variant of the 1937 German Henschel Hs 126 reconnaissance aircraft
  • Ju 87 A-0, a variant of the 1936 German Junkers Ju 87 dive bomber aircraft
  • Me 210A-0, a pre-production variant of the 1943 German Messerschmitt Me 210 heavy fighter aircraft

Submarine

  • Isaac Peral (A-0), a Spanish submarine

See also

  • AO (disambiguation)
  • 0A (disambiguation)