2.1.1773 Part 4 Section 184.108.40.206, FmlaGroup (Linked Formula - Group Box)
a. The standard implies that the cell reference specified by this element is saved into the file.
Excel removes this element and saves the cell reference it specifies on the FmlaLink element of the first radio button in the group. If no radio buttons exist in the group, the value is not saved in the file.