Semantics of `FORMULA` unclear when `RIGHTS` = `CREATE`

[mjacoby]

The semantics of FORMULA are unclear when RIGHTS = CREATE.

For RIGHTS = READ, FORMULA can be understood as an expression describing which elements can be read.
For RIGHTS = CREATE, it is not clear what the expression actually means and what it is evaluated against.

What exactly does FORMULA describe/refer to when RIGHTS = CREATE?

• the parent/container in which a new element may be created

• the type of element that may be created

• something else?

• I have signed the required Developer Certificate of Origin (DCO) already.