Bidirectional transformation of Romanian coordinates between the Stereo 70 national projection and ETRS89, following the official ANCPI algorithm.
Grid envelope: The rectangular bounding box of a transformation grid. A coordinate outside it cannot be transformed at all. Avoid: Grid extent, coverage area, outside grid (for no-data cases)
No-data zone: An area inside the grid envelope where the grid holds no valid values, typically just beyond the national border. A coordinate here is inside the envelope but still cannot be transformed. Avoid: Out of grid, outside grid
Untransformable point: A point that falls outside the grid envelope or in a no-data zone; its output carries a warning naming which of the two applies, never a coordinate. Avoid: Failed point, invalid point