I noticed today that PostgreSQL doesn't support parsing ISO 8601 timestamps that use a comma as the decimal separator.
The section of the standard that describes this is 4.2.2.4
the decimal fraction shall be divided from the integer part by the decimal sign specified in ISO 31-0, i.e. the comma [,] or full stop [.]. Of these, the comma is the preferred sign
I noticed this issue because a script I wrote used the unix `date` command to generate a timestamp (later fed into PostgreSQL)
$ date --iso-8601=ns 2025-10-10T10:38:59,386724473+11:00