symbols to be connected to Field values

[sanbrock]

A formalism to enable connecting Field values to symbols would help a lot in data verification when checking dimensions.

Another point it is to do not only math (nexusformat/definitions#1084) with symbols, but also enable bool algebra. We could then express rules, like "If a>2 then b=3*a else b=1"
Such symbols could also be used not only for dimensions, but also min/maxOccurs.

[benajamin]

The NIAC likes the ideas put forward here and encourages you to prepare a more complete proposal.