There are 8 columns in each data file. They are:
YYYY, MM, DD, P(0.1mm), QCdP, flg, HomoP, flg
The column widths of each column (from left to right) are: 5, 3, 3, 9, 9, 4, 9, 4. 
Column 1 “YYYY”: The year of the data record for the station, a 4 digit number. E.g., 1840, 2018
Column 2 “MM”: The month of the data record for the station. E.g, 1, 2, 3, …, 12.
Column 3 “DD”: The day of the data record of this monthly data file is ‘0’. This is included in the data file for compatibility with ingesting the data in the RHtest program.
Column 4 “P(0.1mm)”: This is the original monthly total precipitation in units of 0.1mm. E.g., if the monthly precipitation value is 45mm. The P(0.1mm) value in column 4 is 450. Please refer to Wang et al. (2023) on the methodology to tabulate monthly precipitation total from daily precipitation. 
Column 5 “QCdP”: This is the gap-infilled and quality controlled monthly precipitation in units of 0.1mm, the same format as Column 4 (P(0.1mm). Please refer to Wang et al. (2023) and Cheng et al. (2023) on the gap-infilling and quality control process. 
Column 6 “flg”: This is a QC flag of the data record if the data (Column 4) was gap-filled (Column 5) using ANUSPLIN Estimation, ‘AE’, or by using an estimation based on the original monthly precipitation, ‘OE’. Please refer to Wang et al. (2023) for more details on the gap-filling methodology.
Column 7 “HomoP”: This is the homogenized monthly precipitation in units of 0.1mm, the same format as Column 4 and 5. Please refer to Wang et al. (2023) for details on the homogenization methodology.
Column 8 “flg”: This is a combination of a ‘H’ homogenization flag and the Column 6 flag. ‘H’ flag is added if the data in Column 7 was homogenized. Therefore, the flag in Column 8 could either be blank, ‘AE’, ‘OE’, ‘H’, ‘AEH’, or ‘OEH’.

References:
Wang, X. L., Y. Feng, V. Y. S. Cheng, and H. Xu, 2023: Observed precipitation trends inferred from Canada’s homogenized monthly precipitation dataset. J. Climate, https://doi.org/10.1175/JCLI-D-23-0193.1, in press.
Cheng, V. Y. S., X. L. Wang, Y. Feng, 2023: A quality control system for historical in situ
precipitation data. Atmosphere-Ocean, Under review.

