Tables
A database is made up of tables. Each table consists of many records, each with the same number of fields.

One way to think of tables is to look at a standard wall calendar. It has rows for each week, and columns for each day of the week. Each individual day has a box (or cell) you can write appointments in. If you have swimming every Thursday you would put the same data, "swimming", in each Thursday box. You know swimming is on Thursday by the column it appears in. If there are no appointments, no data, in other days, "swimming" still shows up in the same box.

The same is true of the GCD:

The lines that define the boxes on a calendar are replaced by the tab characters of our format. Our boxes are called fields and are as wide as they need to be (up to 255 characters), and we aren't concerned with the boxes lining up visually on the screen when we enter data. It is important, however, that each record in the table has the same number of fields, and that the order of the fields is the same.

Aquaman vs Spam [tab] Martin Egeland [tab] Howard Shum [tab] Peter David
Aquaman Tries to Floss [tab] Steve Epting [tab] Norm Rapmund [tab] Dan Jurgens
Aquaman Gets Canned [tab] [tab] [tab] Mike Carlin

The reason for the blank line in the index file is to separate two tables. The indexer record doesn't go into a table, but the series record (which has fourteen fields) goes into a series table, and the issue data (which has eighteen fields) goes into an issues table.