We took those physical properties and made them into logical properties in the file system. The first property is that the files are very closely associated with their physical storage. You did not put more than one file on a tape and did not like to put a single file on multiple tapes if you could help it, which was a reasonable restriction for obvious reasons. If you wrote past the end of your file, you would have overwritten the start of someone else's file. The file system would count off so many bytes or bits for the datatype of the field it was reading or look for a field separator, and then stuff whatever value it found into the local variable.
Fields have an important order in the record.
The data in the file can be almost anything, even if it is dead wrong. People building data warehouses from legacy data sources are discovering just how bad old data can be. A column in a table can have very elaborate constraints on it, so one is much more sure of its correctness. A good database excludes bad data, and does not have to depend on application programs for this function. On a tape, records are in sequence.