In the Options window, navigate to the Loan Options tab and click "Add" (1).

In the Add/Edit Loan Rule window, select "Reference" (1) in the Item Field Value box.

Leave the Borrower Field Value box unselected.

Enter "0" in both the Loan Period and Quantity Limit (2) fields.

Click "OK" to save the rule.

The new circulation rule will now appear in the Rules (1) box.

To test the rule, open the Check Out section.

Scan or manually enter the barcode from the reference book label.

A warning message will be displayed: "This item cannot be checked out (can only be used in the library)".

Enter "Reference" in the TYPE data field.

Question:
Where/how do I set up that my Reference books cannot be checked out? Is there a way for me to do that for all Reference category books at once?

Answer:
Circulation rules can be defined in the Options/Loan Options window. You can establish a single rule stating that "reference books cannot be checked out," which will apply to all your REFERENCE items.