Related Rule
Canada
Practice relating to Rule 66. Non-Hostile Contacts between the Parties to the Conflict
Section A. General
Canada’s LOAC Manual (1999) provides:
Negotiations between belligerent commanders may be conducted by intermediaries known as parlementaires. The wish to negotiate by parlementaires is frequently indicated by the raising of a white flag, but any other method of communication such as radios may be employed. 
Canada, The Law of Armed Conflict at the Operational and Tactical Level, Office of the Judge Advocate General, 1999, p. 14-1, § 3.