The field in the Dataset Management listing will sometimes show a "-" instead of a "Y" or "N".
What does the "-" mean?
When I look at TSO, the dataset is cataloged. I would expect to see "Y" in that field.
In fact the information for each Object View is always explained into the associated Object Help screen.
For this Dataset Management, here is what it is written:
Cat Y, N or - to indicate the catalog status of the data set.
"-" means that the catalog status has not been checked, and field CVols will be blank.
Y means that the data set is cataloged to the displayed volume, and field CVols will be between 1 and 255.
N means that the data set is not cataloged to the displayed volume, and field CVols will be between 0 and 255. It will be 0 if there is no catalog entry. It will be 1 to 255 if there are cataloged volumes, but none match the displayed volume.
The number of volumes to which the dataset is cataloged. If the catalog entry has not been checked, this field remains blank. If the catalog entry has been checked, it displays the number of volumes that were found in the catalog, from 0 to 255.
You can use other object "Uncataloged Data Sets" (DSNUCTL) which is created by running audit script DSNUCTL to find uncataloged data sets on your system.