timestamp_format property controls how dates and times appear in the deliverable’s audit log. It uses MomentJS format tokens.
If not specified, the account’s default timestamp format is used. Set your account default in the dashboard settings.
Setting the timestamp format for an envelope
Format tokens
Use these tokens to build a timestamp format string:
Supported date separators:
/, -, ., or a space.
Supported time separators: : or ..