Keynote File Parsing about table element

Hello,

I am writing a parser to parse keynote files and now I have some doubts about parsing tables. Please help me.

The followings are a part of table cells in tabular-model node in keynote xml file.

- <sf:datasource sfa:ID="SFTConcreteTableDataSource-0">

- <sf:t sf:h="172" sf:w="59.928574" sf:ct="1798" sf:s="SFTCellStyle-136" sf:f="36">

<sf:ct sfa:s="the 56th cell">

</sf:t>

</sf:datasource>

How can I know the relationships between the cell index and the cell's datasource? What does the value of sf:ct represent? Does anyone have schemas of keynote xml files? The schemas doesn't seem to exist in Appls's offical website.

Thanks in advance.