This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
attr.tableId_rowNum is pure display tag feature to give you the row number and you can use it for indexing your rows... where "attr" is of display tag "tableId" is your tables id, and "rowNum" again is of display tag. "-1" is to start the first row or the header to be counted that display tag adds p to your list. hope you know the Ognl expressions used in this.