Looking at the xml of an excel spreadsheet, I see these cells under sheetData/row:

```
<c r="T1" s="23" t="s"><v>17</v></c>
<c r="AP1" s="98"><v>28</v></c>

```

By looking at the spreadsheet, I can see that the first cell is a string (which I can look up in the sharedStrings file), and I know that the second one is the value "28", from which I hypothesise that if a cell has the attribute `t="s"`, it is a string, otherwise it is a value. Is this correct?

I am guessing that the r, s, and t stand for 'row', 'style', and 'type', but can someone clarify for me what they mean and what the possible values for them are? E.g, I see some cells with the attribute t="str", is that the same as "s" or does it mean something special?

I couldn't find any documentation or specification for the excel xml files, so if such a thing exists it would be helpful to be pointed in it's direction.