date

In prior versions of HL7, this data type was always specified to be in the format YYYYMMDD. In the current and future versions, the precision of a date may be expressed by limiting the number of digits used with the format specification YYYY[MM[DD]]. Thus, YYYY is used to specify a precision of "year," YYYYMM specifies a precision of "month," and YYYYMMDD specifies a precision of "day."