Each of the data tables in the database (Sites, Customers, Reservations, Transactions, etc.) are made up of a list of Fields. The fields included in the tables are user-definable to a certain extent, adding to the flexibility of the software. For instance, if you don't have a need to ever know about the Estimated Arrival Time for a reservation, you can disable that field and it will be removed from the database. Besides saving disk space, the disabled field will be removed from the dialogs resulting in a cleaner view and slightly faster data entry.
Many of the fields are "Fixed", which means that they cannot be disabled. These fields are crucial to the operation of the software, such as the reservation start date. Others are optional and can be enabled or disabled as needed, as in the example above.
A note about field values -- all fields can have a "blank" state in addition to having data in them. This saves both space and confusion -- for instance, the "number of children" field for customers is blank (unknown) unless you enter a value for it -- it does not assume (or show) "0" children unless you actually enter "0". However there are some cases where "blank" is the same as assuming a value, such as yes/no fields. Blank is assumed to mean "no" for fields like the customer's "Good Sam member" field. In other words, if you don't check the Good Sam box on the customer entry dialog, it assumes "no".
There is a special category of fields called "Attributes", which appear in the Reservation table and the Sites table. There are dozens of attributes, like "Has 50 Amp", "Waterfront", and "Pad Type". These are used primarily for selecting Site Preferences for a reservation. Once the preferences have been selected, the list of sites available will show only sites that have matching attributes. Thus you can easily match a customer to a site that will meet his or her needs the best. Many of the pre-defined attributes won't apply to your particular campground, so you can disable these or rename them to something more useful. For instance, if none of your sites are waterfront but you have some desirable cabins that are cliff-side, just change the text from "waterfront" to "cliff-side".
Finally, some of the customer and reservation data fields can be renamed and used for different purposes. For instance, you can change "# Pets" to "# Meals", or "Phone 2" to "Cell Phone".
Note that once the database is in use, you can still enable and disable fields or change their text. However, be aware that any data in newly-disabled fields will be lost even if you re-enable the field later (assuming the database is saved to disk and reloaded before re-enabling it).