This is a command to change a links reference from one sheet/workbook to another when both are known.
Straight from Excel help...
ChangeLink Method
Changes a link from one document to another.
Syntax
expression.ChangeLink(Name, NewName, Type)
expression Required. An expression that returns a Workbook object.
Name Required String. The name of the Microsoft Excel or DDE/OLE link to be changed, as it was returned from the LinkSources method.
NewName Required String. The new name of the link.
Type Optional Variant. The link type. Can be one of the following XlLinkType constants: xlLinkTypeExcelLinks or xlLinkTypeOLELinks. The default value is xlLinkTypeExcelLinks. Use xlLinkTypeOLELinks for both DDE and OLE links.
example...
ChangeLink Method Example
This example changes a Microsoft Excel link.
ActiveWorkbook.ChangeLink "c:\excel\book1.xls", _
"c:\excel\book2.xls", xlExcelLinks