When printing a DateTime value into a TOML file, TOML.jl appends a "Z" to the end of the DateTime. The "Z" indicates that the timestamp is in the zero offset zone for UTC. Since DateTime does not carry timezone information this Z can be erroneous. The TOML spec indicates that the bare timestamp with no timezone information is spec compliant. Given the lack of timezone information this is a better default for TOML.jl.

In my particular instance I was writing output that was in ESD (UTC -4). While the offset wasn't particularly important in my case, the Z caused confusion when a colleague saw it. I can of course manually adjust my timestamp to UTC zero before exporting but TOML.jl should not make this assumption.

Here is an example where the Z is appended without any knowledge about the timezone.

julia> TOML.print(Dict("Date" => DateTime(2024,10,22,12)))
Date = 2024-10-22T12:00:00.000Z

I believe instead the above should generate the output Date = 2024-10-22T12:00:00.000 which meets the TOML spec and does not make unfounded timezone assumptions.