Although the scale is intended, in connection with television, to apply to overall picture assessment, it should be noted that the same scale could be used for a critical assessment of particular picture characteristics. Moreover, the number of the grade can be taken as either a quality assessment or an impairment assessment. Depending on the context, for example, a Grade 3 picture is of fair quality, having slightly annoying impairments. The same scale can be used in the case of types of transmission other than television.
ITU-T N.67 SPANISH-1993 history
1993ITU-T N.67 SPANISH-1993 MONITORING TELEVISION TRANSMISSIONS - USE OF THE FIELD BLANKING INTERVAL