A spirit level comprising a body having a level face for setting a surface, at least one bubble vial mounted in the body, the bubble vial having a longitudinal axis generally perpendicular to the level face, and an optical transfer element fixed to the body which transfers an image of the bubble vial to a viewing plane generally parallel to the level face. The illuminating device includes a light source, and a housing adapted to house the light source. The extensible framework can further comprise a context component that determines the context, including context of an application associated with the target object, existing objects associated with the target object, and relationships between the existing objects. The use of a narrow reinforcing layer of woven polyester, nylon or non-woven ultra-fine fibrous material in the seam tape allows the seam tape to be flexible enough to move with the fabric it joins, reducing the incidence of tape edge abrasion. An accessibility packet is received from the accessory.