We have documentation for these two functions: https://help.libreoffice.org/Calc/Mathematical_Functions#GCD_ADD https://help.libreoffice.org/Calc/Mathematical_Functions#LCM_ADD They were renamed to GCD_EXCEL_2003 and LCM_2003 so the documentation needs to be updated as well: https://cgit.freedesktop.org/libreoffice/core/commit/?id=91e15edd12dee222bd5fb0b8912d4daa24d6ea74
Gabor Kelemen committed a patch related to this issue. It has been pushed to "master": http://cgit.freedesktop.org/libreoffice/help/commit/?id=6d24687976074e3bf84dcc4d373cc8a208b4e299 tdf#102206 Change suffixes of LCM_ADD and GCD_ADD to _EXCEL2003