All are true of standardized mortality ratio except -
Standardization is most commonly used for age.
Standardization can be used not only for age, but also sex, race, parity, etc.
SMR is the ratio of observed death to expected death and it is usually expressed as a percentage.
SMR is commonly used in occupational studies for comparison of morality in an industry and general population.
SMR can be used for occurrence of disease (rather than death).