In support of various reanalysis projects, DSS has created a station library for use with the MDL U.S. and Canadian Surface Hourly Data. In order to apply the station library to the reports in the dataset, 34 packed binary bytes have been prepended to each ascii data record. These 34 bytes contain the library information as well as some other information. No changes were made to the original data and the format of the ascii portion of the record is unchanged. This means that the 1976-1996 data and the 1997 and later data are in different formats. Each record has also been written using the DSS RPOUT format. Software is available to decode this data.