GEDCOM is the native file format used by MagiKey FamilyTree.  GEDCOM files are written in plain text, and use the extension .ged to indicate they follow the GEDCOM standard.

GEDCOM is an acronym meaning GEnealogical Data COMmunication. It is a standard that was developed by the Family History Department of The Church of Jesus Christ of Latter-day Saints to enable the exchanging of data between genealogy program. 

MagiKey Family Tree recognizes and uses the Standard GEDCOM version 5.5, with some additions for local use.  You can export files from MagiKey Family Tree which remove these locally modifications to be more easily used by other programs.

More information on the GEDCOM standard is available at http://www.familysearch.org/eng/Home/FAQ/faq_gedcom.asp