Property Mapping in charts were introduced in LibreOffice 4.3 and never properly documented in the Help. Help page to improve: source/text/schart/01/wiz_dataseries.xhp Sources https://wiki.documentfoundation.org/ReleaseNotes/4.3#Property_Mapping https://mmohrhard.wordpress.com/2014/05/29/property-mapping-in-charts/ https://books.libreoffice.org/en/CG248/CG24806-CreatingChartsAndGraphs.html#toc46
correction source/text/schart/01/wiz_data_series.xhp
Olivier Hallot committed a patch related to this issue. It has been pushed to "master": https://git.libreoffice.org/help/commit/8dee39a0fae12660e982dc74cea1d29721bdc946 tdf#167137 Explain the use of "Property Mapping" in Charts