private System.String ExpandWorkOrderVariables( System.String @string ) {
	@string = @string.TrimToNull();
	if ( System.String.IsNullOrEmpty( @string ) ) {
		return null;
	}
	foreach ( var @var in ( this.Variables ?? new Variable[ 0 ] ) ) {
		@string = @string.Replace( "%var:" + @var.Name + "%", @var.Value ?? System.String.Empty );
	}
	return @string;
}