AND: "Patient Characteristic Birthdate: (start datetime >= 01/01/1965)"
AND: "Patient Characteristic Birthdate: (start datetime <= 12/31/1992)"

A measure requires that all patients born between 1965 and 1992 are included in the initial patient population (i.e., a population cohort). There is not a clear mechanisms to express that birth date occurs before or after a specific date, e.g.,:
"Patient characteristic, birth date: (date >= 01/01/1965)"
"Patient characteristic, birth date: (date <= 12/31/1992)"
Does an attribute of "date" make sense for Patient characteristic, birth date?
And will change to Patient characteristic, age make the expression of this requirement even harder?

The clinical reason is that blood transfusions were not screened prior to 1992 so patients born before that date are at risk for Hepatitis C.