code: function validateDomainType() {
  			if (!parent._domainType.hasOwnProperty(options.domain) || options.domain === "min" || options.domain.substring(0, 2) === "x_") {
  				throw new Error("The domain '" + options.domain + "' is not valid");
  			}
  
  			if (!parent._domainType.hasOwnProperty(options.subDomain) || options.subDomain === "year") {
  				throw new Error("The subDomain '" + options.subDomain + "' is not valid");
  			}
  
  			if (parent._domainType[options.domain].level <= parent._domainType[options.subDomain].level) {
  				throw new Error("'" + options.subDomain + "' is not a valid subDomain to '" + options.domain +  "'");
  			}
  
  			return true;
  		}
docs: Ensure that the domain and subdomain are valid
  
  @throw {Error} when domain or subdomain are not valid
  @return {bool} True if domain and subdomain are valid and compatible