If in the portal table you create an unstored calculation field - say, cRecordNumber - with the expression Get ( RecordNumber ), you can refer to it in the Conditional Formatting calculation like so:
rec = PortalTable::cRecordNumber ;
GetNthRecord ( PortalTable::hours ; rec ) <> GetNthRecord ( PortalTable::hours ; rec - 1 )
i.e. this row's values is different from the previous row's value.
Yeah! It worked. Thank you so very much.