Package subtoken is spikes (b) and (c) of tasarim-v6 §5.5:
Example
1(b) a grc721 token created with a sub-realm identity cur.Sub("c/1"):
2 does NewToken accept it, what is Token.ID(), and can the host spend
3 coins that land on a sub-address ("roy/1") with a banker bound to
4 cur.Sub("roy/1")?
5(c) a grc721 Extension that vetoes every transfer and burn until a
6 reveal flag flips, while mints keep working.
One token, one collection, no owner: anyone may call every function. Never part of the product.