static private function isValidFilename( $pFilename )
	{
		// A filename must not contain the following chars:
		$invalidChars = [ ',', '<', '>', '*', '?', '|', '\\', '/', "'", '"', ':' ];
		// Build regular expression.
		$invalidCharRegExPatter = '@'. implode( $invalidChars ) . '@';
		// Notify the developer when a filename contains invalid characters.
		if ( \preg_match($invalidCharRegExPatter, $pFilename) === 1 )
		{
			\trigger_error( 'A filename cannot contain the following characters: ' . implode('', $invalidChars) );
			// When trigger errors are silenced.
			return FALSE;
		}
		return TRUE;
	}