Comprehensive quality evaluation may have different scoring methods in different evaluation systems. Usually common classification is to use letter grades, such as A, B, C, D, etc. These grades are usually used to indicate different comprehensive quality levels or scores.

Although some evaluation systems or specific fields may be distinguished by other symbols or more levels, such as adding S-level, E-level and F-level. It is not a universal standard. Each evaluation system has its own classification and standards, which are graded according to specific requirements.

Therefore, generally speaking, comprehensive quality evaluation usually uses four grades, A, B, C and D, to express different levels or scores, but there is no generally accepted S grade or E and F grade. Please note that this may change due to different evaluation systems and environments.