Use ISO time standard

[jg2345]

I have been programming for over 40 years and doing web development for 30 and I have never seen "epoch" used. Also, the documentation on it's interpretation is not completely clear indicating folks will misinterpret it on a regular basis. I would recommend ISO 8601 time standard which is widely used and easy to understand.

[cportele]

Meeting 2025-09-15: The epoch of a coordinate is an important concept for coordinate reference systems that change over time (dynamic CRS), e.g., due to tectonic motion. The concept and its representation as a decimal number are specified in detail in OGC Abstract Specification Topic 2: Referencing by coordinates. JSON-FG simply provides a representation in JSON. To change the representation in JSON-FG would first require a change in Topic 2.