Curtains are also used for privacy and security. They act as a functional covering for an enclosement or a room. Come to think of it: Curtains are used inside the bathroom, curtains are also used in private bedrooms, curtains are also used in the kitchen. For most people privacy is a primordial concern. Curtains prevent other people from peeking right into your personal space.
Your question above seems to be somewhat vague, but would like to see. if we can flush that out a bit. A solution document may be a. Solution Engineering, Solution Architecture, Solution. Integration, Technical Solution, Solution Design, or Solution. Build document.
A solution is a mixture of one substance dissolved in another so the properties are the same throughout. A solution is composed of a solute and the solvent. The solute is the substance being dissolved and the solvent is the part of the solution that does the dissolving.