When you double-click on an XML file created by ExcelXP, Excel isn't opened directly. Instead, the XML file is opned by another program, MSOXMLED, which scans the file looking for more specific information on what to do next, such as "". If it finds that line, it passes the file name to Excel; if it finds another program name, it uses that; and if it doesn't find anything that can help it decide what program to use, it opens the XML file for viewing in Internet Explorer.
A SYLK file, on the other hand, is opened directly by Excel. It's a very old file format.
If I run the code in your example and navigate to c:\temp in the SAS Explorer, I see an Excel icon for the file, and double-clicking on it opens Excel. I'm not sure what you're doing when you say that the SAS Results Viewer shows you an XML icon. Perhaps if you went into the SAS registry editor and set up an entry for the SYLK filetype, SAS would handle it correctly. I don't know.
That tagset was written to address a specific need, and as a starting point to learn about tagsets. I was unable to find documentation explaining all the options and inter-relations between the different parts of a SYLK file, so the results are very rudimentary. Now that XML is available, SYLK is probably not the best choice for getting data into Excel (unless, of course, you're still using Excel 5 or below).
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