LibreOffice exists since 2011, as the non-Oracle controlled follower of OpenOffice.org, although OpenOffice continues to exist.
You can use LibreOffice < 4.0 in GECAMed as well as OpenOffice.org. But we recommend to use OpenOffice for the GECAMed-Letter-Module.
If you want to use LibreOffice, but you haven't configured OpenOffice.org, yet, it's no problem. Simply open a template or create a new letter and GECAMed will ask you for the installation path of your OpenOffice.org. Just tell GECAMed the path to your LibreOffice, instead of the OpenOffice.org path and GECAMed will use LibreOffice. If you already configured OpenOffice.org for this PC, you need to change the GECAMed.properties file.
Open the GECAMed.properties file in a text editor. Here we explain how to find it.
Search for the line, that starts with “OO_INSTALLATION=”. This will be followed by your OpenOffice.org or LibreOffice installation path. To change the usage of your office software, you need to enter the installation path of the office you want to use.
If you did a default installation, you can just switch “OpenOffice.org” to “LibreOffice” or vice versa.
Here is a script, to set the Office version for MacOS for the current user from OpenOffice.org to LibreOffice and from LibreOffice to OpenOffice.org.