Figure 4.2. Incandescent lamp parts.

Bulb Shapes
Incandescent lamps are available with a number of different bulb shapes as shown in figure 4.3. The normal bulb shape of the common household lamp is called GENERAL LIGHTING SERVICE (gls). However, the American term is Arbitrary hence the abbreviation in the order code of A1. PAR and REFLECTOR shapes are specific functional designs to concentrate the light in one direction. PAR is short for Parabolic Aluminised Reflector. The other shapes are primarily decorative variations.

Figure 4.3. Incandescent bulb shapes. Lamp Caps