Get root directory.
${GetRoot} "[FullPath]" $var
Section
${GetRoot} "C:\Program Files\NSIS" $R0
; $R0="C:"
SectionEnd
Section
${GetRoot} "\\SuperPimp\NSIS\Source\exehead\Ui.c" $R0
; $R0="\\SuperPimp\NSIS"
SectionEnd
Written by Instructor