Why subClass of 'logistic unit'?

[schneidert]

https://github.com/iofoundry/ontology/blame/a57540171b0ad2a8c312a0b223876b9ee3f20081/supplychain/SupplyChain.rdf#L1671

Why must a 'material trade item' be a subClass of a 'logistic unit'?

'material entity' and ('continuant part of at some time' some 'logistic unit')