Text links can be locked by the Document Owner in order to prevent inadvertent changes from occurring.
To learn more about creating text links, read the article Linking Overview.
Adding Locks to Text Links
To lock a text link, highlight the entire link and choose Lock Text Links from the Lock Link menu on the Data tab. Locked text links will be indicated by a grey underline on the right of the green link indicator for text links in the Accounting, Currency, Date, Number, Percent and Period categories.
If you lock a text link in the Automatic or Text categories, a gray triangle will appear in the upper left-hand corner of the link.
Unlocking Text Links
If you try to remove a locked text link, you'll get a warning that the link must be unlocked before you can delete the selection.
To remove a lock from a text link, select the link and choose Unlock Text Link from the Lock Link menu in the Data tab. The link indicator will return to a solid green line. Be sure to Share your section or document after locking or unlocking text links.
You can also lock or unlock groups of text links. Highlight the paragraph(s) containing the links you wish to change and select lock or unlock as described above.
NOTE: Source values in workbooks and tables that are associated with locked text links can be edited as needed.