(1) “Actual physical improvement” means the actual physical change in, or alteration of, real property as a result of labor provided, pursuant to a contract, by a contractor, subcontractor, or laborer which is readily visible and of a kind that would alert a person upon reasonable inspection of the existence of an improvement. Actual physical improvement does not include that labor which is provided in preparation for that change or alteration, such as surveying, soil boring and testing, architectural or engineering planning, or the preparation of other plans or drawings of any kind or nature. Actual physical improvement does not include supplies delivered to or stored at the real property.

  (2) “Co-lessee” means a person having an interest in real property, the nature of which is identical to that of the interest of the lessee who contracted for the improvement to the real property, whether the extent of such interest is identical or not.

  (3) “Construction lien” means the lien of a contractor, subcontractor, supplier, or laborer, as described in section 107.

  (4) “Contract” means a contract, of whatever nature, for the providing of improvements to real property, including any and all additions to, deletions from, and amendments to the contract.

  (5) “Contractor” means a person who, pursuant to a contract with the owner or lessee of real property, provides an improvement to real property.

  (6) “Co-owner” means a person having an interest in real property, the nature of which is identical to that of the interest of the owner who contracted for the improvement to the real property, whether the extent of such interest is identical or not.