The release notes for 2019.r3 state the following changes has been made to DateTime:
57937 Framework » All DateTime: added new ToString function that accepts a format string according to these guidelines: https://www.unicode.org/reports/tr35/tr35-57/tr35-dates.html#Date_Field_Symbol_Table
There is no example for this change in the language reference, and autocomplete doesn’t show a way to implement a custom format string via this change.
Xojo: can you post a simple example here???