Ayanamsha
The angular offset used to convert a tropical longitude to a selected sidereal zodiac.
Definition
Different sidereal schools use different ayanamsha models. Lahiri/Chitrapaksha and Krishnamurti values are close but not identical, so signs or Nakshatras near boundaries can differ between systems.
Example
If two sites use the same tropical planet longitude but different ayanamshas, their displayed sidereal longitude can differ without either ephemeris being broken.
AstroVedic360 labels the ayanamsha used by each calculation path; KP uses its separately disclosed convention.