I recently completed a roof project for a relative. This was roof #3 for the home- tore off the previous two layers. The home is about 40 years old with roof trusses and 1/2 (maybe 7/16) plywood sheathing, no clips. Plenty of roof and eave ventilation. As expected, the roof deck seemed to be quite brittle. A 220# guy with a bundle of shingles in hand could have stepped through the roof quite easily.
DSLR Definition: Digital Single Lens Reflex Camera. The Nikon D3000 is a DSLR camera. A DSLR, or digital single lens reflex camera is an advanced type of digital camera that provides high-level image quality, performance levels, and manual control options, typically much better than what you'd receive with a fixed lens camera.
A visitor location register (VLR) is a server in a cellular network that supports roaming functions for users outside the coverage area of their own HLR.