Request for standard metadata and geometry representation of concrete pours and pour breaks

Originally raised by lassi.liflander [here](https://forums.buildingsmart.org/t/new-entity-needed-to-ifc5-for-mould-to-represent-the-mould-faces/1090), quite a fundamental aspect of concrete pours and pour breaks seem to be missing from IFC. I am also facing this issue more recently in construction sequencing where nominating pours and pour breaks is quite vital in 4D.

Is there something in the spec which might already be useful?

Thoughts? Allocating to core and sequencing. Ping @berlotti @TLiebich @aothms @SigmaDimensions