If you enabled the Find word variations option, then Source Insight will also find different ending forms of the keywords you specified. For example, if you specified the keyword “open”, Source Insight will also find “opens”, “opened”, and “opening”. This has the same effect as typing this expression:
(open or opens or opening)
Word variations are applied to each keyword term. For example, if you specified:
save write
Which implies “save” and “write” must be present. With word variations enabled, this search would be equivalent to:
(save or saves or saving) and (write or writes or writing)