Good afternoon,
Part XIII of which section please?  There are many definitions that start with Part XIII such as:
non residents tax obligations: http://www.cra-arc.gc.ca/tx/nnrsdnts/ndvdls/nnrs-eng.html
http://www.cra-arc.gc.ca/tx/nnrsdnts/pyr/prtxiii/wthhldng/menu-eng.html
T2016 Part XIII Tax Return - Tax on Income from Canada of Approved Non-Resident Insurers
http://www.cra-arc.gc.ca/E/pbg/tf/t2016/README.html
You can also contact the CRA: http://www.cra-arc.gc.ca/cntct/phn-eng.html#h1
Thank you,
Leeanne@TurboTax