The Committee on Quality Assessment of Optical Systems, group of the German Standards Institution (DIN) is engaged in the standardization of OTF measurement technique. The state-of-the-art of MTF measurements and calculations shows an agreement of a few percent. This is the result of MTF measurements and calculations performed on two lenses by several laboratories in Germany and in England. Lens No. 1: f/3.2, f = 100 mm, infinite conjugate, angular field up to 12.9°, A = 546 nm, spatial frequencies up to 400 c/mm. Lens No. 2: f/5.6, f = 90 mm, infinite conjugate, angular field up to 45.1°, A = 546 nm, spatial frequencies up to 80 c/mm. The agreement obtained encourages MTF standardization and the use of MTF to describe the optical quality of image-form-ing systems. A report on the results of the committee's work is given. The work is divided into four parts: Sheet 1. Symbols, Definition, Mathematical Relations Sheet 2. Equipment Parameters Sheet 3. Practical Measurement Sheet 4. Evaluation and Representation of Measurement Results.