GAMOL: TDC Corpus Tool

With this option checked, your search will include sentences with your keyword and also sentences with your keyword plus the -ng/na ligature.
With this option checked, searching for the keyword "pula" will show example sentences with "pula" in them, as well as example sentences with the text "pulang" in them. Needing to search for both a keyword and the keyword+ligature is a common requirement, and this search option makes the process faster and easier.