A global indexing scheme designed for the Landsat Program. It is based on nominal scene centres defined by path and row coordinates. See NASA: World Reference System
Formerly xray, it is an open source project and Python package that makes working with labelled multi-dimensional arrays simple and efficient.
Yet Another Markup Language (YAML)
A human-readable data-serialisation language. Originally, YAML was said to mean ‘Yet Another Markup Language’, referencing its purpose as a markup language with the yet another construct. However, it was then repurposed as ‘YAML Ain't Markup Language’, a recursive acronym, to distinguish its purpose as being data-oriented, rather than being document markup.
The point on the celestial sphere directly above the observer, and directly opposite to nadir.