Interpretation of the filename:
The 2 first letters: Country of submission (dk=Denmark, se=Sweden, no=Norway, us=USA, au=Australia, br=Brazil, ca=Canada, ar=Argentina, uk=Great Britain, nl=The Netherlands, nz=New Zealand, fr=France, de=Germany).
The 5 or 6 digits, (y)ymmdd: Year of submission (1997+y), date of submission (mm/dd).
The last letter identifies different files submitted the same day from the same country.

INDIviduals: Number of individuals in the file. The files are sorted after INDIviduals.

Number of Hits: A hit means that at least one individual also occurs in another file. The submitter is notified of each hit. A blank means that the file has not been processed yet.

Number of Warnings: A warning means that there is a problem with the data in the file but the problem is unlikely to reduce the possibility of finding identical individuals in other files.
Warnings are often caused by genealogical software that allows the user to generate non-standard GEDCOM-data, f.ex. dates containing non-english words/abbreviations. The submitter is notified about these problems. A blank means that the file has not been processed yet.

Number of Errors: An error means that there is a problem with the data in the file and that this is likely to reduce the possibility of finding identical individuals in other files.
Most errors concern dates that are decidedly wrong or invalid family-structures, f.ex. a person that is a child in more than one family, or a person that occurs more than once in the file. Most errors are caused by typing errors when the submitter is entering the data into the computer. A blank means that the file has not been processed yet.