When leveraging the link manager in smart forms the existing bookmark field may list some default buttons as shown bellow with a name similar to ek_cf_default_btn.

There is not a method for setting default bookmarks within the link manager of the CMS, and these entries may show up if known issue EKTR-224 is being experienced. To resolve this issue apply the latest cumulative site update (> 9) for version 9.2 SP1