In this forum there is a post call "COM Resources" and in there is a link to the MS Excel constants ... heres a dump of those format values - dont see anything obvious to do with HTML ...

#define xlAddIn 18
#define xlCSV 6
#define xlCSVMac 22
#define xlCSVMSDOS 24
#define xlCSVWindows 23
#define xlDBF2 7
#define xlDBF3 8
#define xlDBF4 11
#define xlDIF 9
#define xlExcel2 16
#define xlExcel2FarEast 27
#define xlExcel3 29
#define xlExcel4 33
#define xlExcel5 39
#define xlExcel7 39
#define xlExcel9795 43
#define xlExcel4Workbook 35
#define xlIntlAddIn 26
#define xlIntlMacro 25
#define xlWorkbookNormal 0xffffefd1
#define xlSYLK 2
#define xlTemplate 17
#define xlCurrentPlatformText 0xffffefc2
#define xlTextMac 19
#define xlTextMSDOS 21
#define xlTextPrinter 36
#define xlTextWindows 20
#define xlWJ2WD1 14
#define xlWK1 5
#define xlWK1ALL 31
#define xlWK1FMT 30
#define xlWK3 15
#define xlWK4 38
#define xlWK3FM3 32
#define xlWKS 4
#define xlWorks2FarEast 28
#define xlWQ1 34
#define xlWJ3 40
#define xlWJ3FJ3 41

-Shawn