Getting Field name from XSL

I was trying to do a custom stylesheet that has a field name 'Start Date Time'.
I was unable to select it from the xsl sheet, after reading http://paulgalvinsoldblog.wordpress.com/2007/12/09/display-content-query-web-part-results-in-a-grid-table/ and listing the fields... it turns out that the field name is NOT

Start_x0020_Date_x0020_Time

BUT

Start_x005F_x0020_Date_x005F_x0020_Time !!!!!!!!!!!!!!!!!!!!

And I don't understand why when I look at field info within list settings, it shows Start_x0020_Date_x0020_Time !