Provide default sorting on a yui:datacolumn

I have defined a yui:datacolum开发者_StackOverflow中文版n like below and wanted to sort this column in a specific way during page load.

yui:datacolumn key="Action" label="Action" sortable="false" 

If I use the below code, I get a "The attribute prefix sortOptions does not correspond to any imported tag library" error message.

yui:datacolumn key="Action" label="Action" sortable="false" sortOptions:"{defaultDir:YAHOO.widget.DataTable.CLASS_DESC}"

I also wanted to underline the label of the column heading to indicate that this column is sortable. How do I do that?

---

One way to underline the label of the column heading:

.yui-skin-sam thead .yui-dt-sortable { 
    text-decoration: underline;
}