The Indian patents act defines an invention as "a new product or process involving an inventive step and capable of industrial application"
Inventive step is defined as "a feature of an invention that involves technical advance as compared to the existing knowledge or having economic significance or both and that makes the invention not obvious to a person skilled in the art."
One of the essential requirements to satisfy the inventive step requirement is that the invention should not be obvious to a person skilled in the art. The other requirement is that a feature of the invention should involve
EITHER
a technical advance as compared to the existing knowledge
OR
having economic significance
OR
both.
The definitions of invention and inventive step are not restrictive in terms of subject matter. However the Indian patents act has a separate section (Section 3 and its sub sections (a) to (p)) that states "The following are not inventions within the meaning of the act."