(ii) where applicable, the chemical formula which, among all the formulae contained in the application, best characterises the invention. (b) The summary shall be so drafted as to enable the clear understanding of the technical problem, the gist of the solution to that problem through the invention and the principal use or uses of the invention. (3) The abstract shall- (a) be as concise as the disclosure permits and shall, as far as practicable, not exceed 150 words; and (b) not contain statements on the alleged merits or value of the invention or on its speculative application. (4) Every main technical feature mentioned in the abstract and illustrated by a drawing in the application shall be followed by a reference sign placed between parentheses. (5) The abstract shall be accompanied by the most illustrative of any drawings furnished by the applicant. . 15. (1) The terminology and the signs shall be consistent throughout the application. (2) Only such technical terms, signs and symbols shall be used as are generally accepted in the field in question, unless otherwise approved by the Controller. (3) Units of weights and measures shall be expressed in accordance with the metric (4) Temperatures shall be expressed in degrees centigrade (Celsius). (5) Density shall be expressed in metric units. system.