Special Considerations for Maintaining Circulation Parameter Tables

Before you edit a circulation parameter table, it is important to understand how the system uses the table and how your change will impact system behavior. Always consult the relevant documentation on the table before you make changes. Below are some special considerations and tips for editing circulation parameters.

• View your library's system messages regularly. When the system finds errors in some parameter tables, it writes those errors to the system messages file. You can use the information in this file to identify and correct the error.
• Use caution when deleting or reordering table entries. In some tables, such as the Loan Rules and Text of Circulation Notices tables, the system identifies entries by their position in the table. Moving or deleting entries can have unintended consequences, such as items circulating for the wrong loan period or incorrect text on circulation notices.
• In some tables, entry order matters. The system reads though each circulation parameter table until it finds an entry that is applicable to the current situation. Some tables are read from top to bottom, some from bottom to top, and some until a complete match is found. In tables that are read top to bottom or bottom to top, you should order your entries so that the system begins with the most specific data and ends with the most general.
• Not all elements can be edited safely. For example, editing loan rule data elements while items are checked out under that loan rule can affect renewals, overdue notices, and billing. Before you edit any part of an entry in a circulation parameter table, make sure you understand how the system uses that element. For one particular example of how changes to loan rules can have unintended consequences on circulating items, see Modifying the Overdue Variables of a Loan Rule.
• Not all tables allow wildcards. Some tables enable you to substitute wildcards (that is, codes that represent more than one value, such as mn* or ?????) for values in certain elements. However, not all tables permit wildcards, and not all tables use them in the same way. Check the documentation on the data element you are editing for information about how to use wildcards.
• Changes might necessitate other changes. The data elements of some parameter tables point to entries in other parameter tables. For example, the Loan Rule Determiner table contains references to the Patron Types table, the Item Types table, and the Branches table. When you change one of these tables, you might need to update other tables as well.
• Document your changes. The system does not retain a log of the changes you make to your circulation parameter tables. Keep notes on the changes you make so that you can identify and undo them if problems arise.