If a record has a value in 776$w, this is used for linking even if UseControlNumber is set to Don't use. To test: 1) Make sure UseControlNumber is set to Don't use 2) In Administration > MARC bibliographic frameworks, add field 776 to the editor 2.1) Go to Administration > MARC bibliographic frameworks 2.2) Next to the Default framework, click Actions > MARC structure 2.3) Search for 776 2.4) Next to field 776, click Actions > Edit subfields 2.5) Go to tab t, check the Editor box 2.6) Go to tab w, check the Editor box 2.7) Click Save changes 3) Go to Cataloging and add a new record 4) Fill in the required fields 5) Enter values in 776$t and 776$w 6) Save the record (no need to add items) 7) Go to normal view in staff interface 8) Hover mouse cursor over the link generated for Additional physical formats --> The link uses the control number 9) Open the record in the OPAC 10) Hover mouse cursor over the link generated for Additional physical formats --> The link uses the control number