Gwai Lo Dan
3rd Black Belt
I'm not positive, but I think it's a requirement for the "member in good standing" status. Not having that makes a competitor's life difficult.
Correct. For example see the bolded section below (from http://www.wtfcanada.com/eng/news/events/national-championships-policies-rules/):
National Championships Ā Policies & Rules
Nov 1, 2012 // by Michelle // Coaches, Events // Comments Off
National Competitions Policy
In order to be eligible to compete in the National Championships being held 9 to 13 January in Vancouver, BC (the ĀNational Championship), a black belt athlete and their designated coaches must (consistent with the National Competitions Policy).
1. Duly register for the competition on or before the registration deadline published by Taekwondo Canada (the ĀRegistration DeadlineĀ); and
2. Have met the standards and/or credentials required by Taekwondo Canada including those:
a. published as part of the competition rules; and
b. for black belt coaches, the National Coaching Standards Policy.
National Championship Rules related to Registration and Credentials
The following requirements are part of the National Championship Rules related to registration and credentials requirements and deadlines.
1. In order to register, by the Registration Deadline, each athlete and coach must:
a. be a member in good standing with Taekwondo Canada; and
b. be a member in good standing with the Recognized Member Organization (RMO), which is the body that is recognized by Taekwondo Canada as representing athletes in the province, with the exception of the Canadian Forces.