there is a dbf file and a text document explaining the list of files in it. Is it the case that the fields in the doc are always present in the dbf for every row? I am beginning to work with dbf.
Yes.
Each row (or record) is a fixed size in the dbf file, and each field takes up a fixed amount of space in that row.
Even Memo fields, which can hold an arbitrary amount of data, only occupy a fixed amount in the dbf file itself -- an integer reference to where in the separate memo file that field's data starts.