  The operation of the future Cherenkov Telescope Array (CTA), the next
generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), as an Open
Observatory requires data products and analysis tools to be accessible and
usable by the scientific community. This requirement has impelled gamma-ray
astronomers to develop open-source science tools and standardised data formats.
The objective of this presentation is to provide a perspective on the current
effort to define a prototypical format for high-level gamma-ray astronomical
data. The initiative, started by the IACT community in 2016, has gained in the
years 2018 and 2019 full recognition thanks to the first public data releases
in such format by current-generation IACTs, followed by a series of papers
employing it either to test the capabilities of open-source gamma-ray analysis
tools or to showcase examples of reproducible, multi-instrument analysis.
