SYLK: file format is not valid

I had a co-worker complain that she was unable to open a CSV file I was generating automatically using PHP. The error she was receiving was “SYLK: file format is not valid”. So I went to Google and searched for it and it turns out that Excel is such a POS that if the first two characters of the CSV file are ID (capitalized) then you will get this error. So I prepended an X to the file and that fixed it. I am fortunate enough to not use Microsoft Office for the past few years. I HIGHLY recommend OpenOffice and the best part is that it is FREE. OpenOffice can read and write the native Microsoft Office formats so you will not have problems shard documents with co-workers. If you are in IT you can save your company a ton in licensing by switching to OpenOffice and never get the ridiculous SYLK: file format is not valid error.