This is a summary of unit values that exist for a site and data descriptor. This summary shows the Data Descriptor number, the unit value data type, the transport code, the begining date of record, the ending date of record, and the number of unit values. The Data descriptor sequence number. A code indicating the type of unit values. The valid codes are meas = Measured,edit = Edited, corr = corrections, shift = Shifts, and da = data analysis.> The date of the first unit value. The date of the last unit value. The number of unit values in the record.