From the Canadian Type Certificate Data Sheet:

"The glider, when weighing for definition of c.g. location and mass value, shall be attituded so, that the wing root-chord /wing chord in wing-to-fuselage plane is level."

Paragraph 21 on page 5 of the TCDS that you can download by clicking on the VIEW PDF Icon on this page:
Tiny URL: http://tinyurl.com/dx7z5hr

Original URL:

http://wwwapps.tc.gc.ca/saf-sec-sur/...bid_n um=1027