This field can contain custom method that returns URL Or URL template if multipage Generation is on - see details below of subject CSS as it should be put in generated result HTML. F.e. if You want converter put some specific URL instead of standard CSS file name into generated CSS then You should just create and put into this property method that generates desirable URL. If flag SplitCssIntoPages set then this custom strategy if any must return not exact URL of CSS but rather template string that after substitution of placeholder with page number with string.Format function inside converter can be resolved into URL for this or that pages CSS URL. Examples of expected return string in such case are SomeTargetLocation-page_0.css../PartHandlers/GetCss.aspxDocumentId45654ampCssPage0...URL template if multipage generation is on - see details below)...CSS as it should be put in generated result HTML. F.e. if You want...