Negative dates

[likescookies]

For some genres, such as classical, I use the date tag to identify the date of composition rather than the date of recording. I'd prefer to browse Bach by the order he composed his works, for instance.

But what if I had an album of works purportedly composed during, say, the Qin dynasty (221-207 BCE)? Could I use negative dates in my ID3v2.4 tags?

My understanding is that ID3v2.4 supports ISO 8601, which according to Wikipedia, which supports negative years "only by prior agreement between the sender and the receiver."

Thus, I assume negative dates wouldn't work, but was curious as to whether I was being pessimistic?