How do I prevent Excel from deciding it knows better then me? In this case, how do I prevent it from reformatting dates without asking or even indicating it has done this?

Situation: attached is a .tab file, similar to one that Excel automunges. Open it in a text editor, and dates appear as 2005-8-15 as they should be. Open the file in Excel, and the same date appears as 8/15/2005. Then when the file is saved, 8/15/2005 is written to it.

I've looked at the hundreds of options Excel has and can't find what does this, and a google search leads me to a ton of sites on how to format dates in proper .xls spreadsheets, but none talking about this type of automunging of non Excel formatted files.