Sign key assigned by Evonet.

Specify application/json; charset=utf-8, which means the message body of the request and response must be in the JSON format, and the character encoding is UTF-8. It will be echoed back in the response message.

The time when the message is sent. The format follows ISO 8601, which is YYYY-MMDDThh:mm:ssTZD. For example, 2021-05-26T10:08:25+08:00. It will be echoed back in the response message.

KeyID is a unique key identifier of up to 36 characters that is generated along with the signature key by Evonet.

An ID for a merchant to trace every API request.
The suggested value is UUID or GUID, such as 2d21a5715c034efb7e0aa383b885fc7a.
It is suggested to specify this value with no more than 32 characters in length.
Evonet will not validate this value and will echo it back in the response message.

Fixed value: Key-based.