Batten:: Roofing battens or ceiling battens. Usually timber members fixed at the truss chords to support roof tiles or ceiling material. Also provides lateral restraint to the truss.
Residential Roof Replacement/Installation
Purlin:: Roofing purlins. Usually timber members fixed at right angles to the truss chords to support roof sheeting. Also provides lateral restraint to truss. Similar to battens except more widely spaced.
Can be built to improve energy conservation: Raising the heel height allows room for more insulation along roof edges and allows it to perform at its maximum efficiency.