How can I write to IPTC:TimeCreated without time zone information

[mortyccp]

How can I write to IPTC:TimeCreated without time zone information ?
Right now exiftool will default to system timezone. I don't to have time zone included.

[StarGeek]

According to the spec, the time zone is required in the IPTC:TimeCreated tag. 

It doesn't look like exiftool allows you to break that requirement.