in reply to Xlxs Parsing Issue
That being said, I have to wonder how much manipulation is needed here. If the idea is to go from .xlxs to the standard(old).xls format, why not just open it in something like LibreOffice and do a "Save As", and choose the version that you need? Last I looked there was some rather large selection of Excel formats, and I seem to recall they include the format you want. Once that is done, use Excel or LibreOffice to manipulate it as you see fit, then save.
I could understand doing this programmaticaly if there were a large number of files that you needed to do it for, but you indicated "an irregular file", so I am assuming a single file.
I find it hard to believe that you are going to get functionality out of Perl that you would not get out of the application(Excel) and its built in scripting without a lot more effort than is really required.
I recognize that there may be other circumstances, but based on what you have written, I would be inclined to ask myself why I want to write a program...
Note that I no longer use Excel, other than to receive the files and open them in an opensource application, and if I have to, save them back to the original format and return them to the sender, so the Excel side of my advice is suspect... .
Good luck with your project!