Briefly describe the following: 'Coinsurance' and 'coinsurance clause'.

Coinsurance: Where the amount of insurance on large industrial complexes is substantial, it is possible for the insured to interest different insurers in the risk for varying proportions of acceptance, so that the total risk is covered. The practice is for each insurer to issue a policy with a specification or schedule giving a description of the property insured, with the "co-insurance clause" included there in. Survey of the risk, rating, collection of premium and preparation of the specification is carried out by the "leading office", that is the office carrying the largest share in the business. All co-insurances are agreed upon prior to the issue of the original policy. In the event of a claim all policies would contribute equally. In case, in rare instances where two policies are extant for a same risk, both would contribute in proportion of their interest in the sum insured at the time of claim. Notably, the polices would contribute in a manner to ensure that the insured is indemnified and not benefitted from the loss.