async loadBCP47Timezones() {
		const oBCP47Timezones = JSON.parse(await fs.readFile(sBCP47TimezonesPath, "utf8")).keyword.u.tz;
		this.aSupportedTimezones = [];
		this.mAlias2SupportedTz = {};
		Object.keys(oBCP47Timezones).forEach((sKey) => {
			if (sKey.startsWith("_")) {
				return;
			}
			const oBCPTimezoneInfo = oBCP47Timezones[sKey];
			if (!oBCPTimezoneInfo._alias) {
				if (!oBCPTimezoneInfo._deprecated) {
					console.log(`ERROR: BCP47 timezone with key '${sKey}' has no _alias and is not deprecated`);
				}
				return;
			}
			const aAliases = oBCPTimezoneInfo._alias.split(" ");
			const sCLDRTimezone = aAliases[0];
			if (sCLDRTimezone === "Etc/Unknown") {
				return;
			}
			this.aSupportedTimezones.push(sCLDRTimezone);
			// add also the first timezone ID to have a complete list of BCP47 time zone IDs
			aAliases.forEach((sAlias) => {
				this.mAlias2SupportedTz[sAlias] = sCLDRTimezone;
			});
		});
	}
Loads the BCP47 timezones package and creates two instance attributes:
<ul>
  <li><code>aSupportedTimezones</code>: Contains the array of not deprecated CLDR time zone IDs</li>
  <li><code>mAlias2SupportedTz</code>: Maps each alias from the BCP47 data to the corresponding not deprecated
    CLDR time zone ID</li>
</ul>