Artikel 77

Spaces or parts of spaces referred to under item (d) of Article 76, designated as light and air spaces, shall, on an application by the owner, be added to the ship's gross tonnage and to the propellingmachinery space on which the allowance for propelling-power is to be based, provided that they are:
(a) reasonable in extent;
(b) certified as safe and seaworthy;
(c) so constructed, that they cannot be used for any purpose other than the admission of light and air to the machinery space or for such machinery, appliances or apparatus as may be regarded as forming part of the propelling-machinery, in conformity with the provisions of Articles 78 and 79.
The formulae of measurement should indicate whether the spaces in question fulfil the conditions mentioned above.