IFC resource concepts
Resources represent things which can be consumed in a process which have an associated cost or scheduling impact.
A role manages a resource

An organisation, person, or role is responsible for managing, allocating, delegating, and scheduling usage of a resource.
A role consumes a resource

An organisation, person, or role is performing some form of work that consumes a resource.
Resource availability restrictions

A resource is only available on certain dates and not others.
A resource is an asset

A resource is an asset. Although not shown, the asset may then be owned by an organisation as described in IFC group concepts.
A resource is consumed by a task

A resource is consumed by a task.
A resource may be consumed by a particular quantity during execution of a task

10m3 of concrete is consumed by a task.