From BlenderWiki

This panel appears in the Shading Context panel group which is accessed using F5 or clicking button in the Buttons window and a Lamp must be selected.

[edit] Texture and Input

• Tex - Texture Channels. A Lamp has multiple channels within which Textures can be linked. Each channel has its own mapping (i.e. the manner in which the texture works on the lamp). Additional settings are in Shading's Map To panel.
• TE: - The name of the Texture.
• - Select an existing Texture from the list provided, or create a new Texture.
• Clear - Textures can be linked. This clears that link.
• 1 - If the Texture has multiple users (i.e. multiple links), this button shows the total number of links that are referencing this Texture.
• - A name will be generated automatically.
• Glob - The global coordinate is passed on to the texture.
• View - The view vector of the lamp. The vector of the global coordinate to the lamp is passed on to the texture. If the lamp is a Spot, the view vector is normalized to the dimension of the spot beam, allowing use of a Spot to project a slide. A Gobo type Lamp.
• Object - The Object used as source of co-ordinates. The Object name must be entered in the Text Button directly below this button.
• d(X,Y,Z) - The extra translation of the texture coordinate.
• size(X,Y,Z) -The extra scaling of the texture coordinate.