Sorry, Goodreader is not the solution.
The Goodreader browser cannot download my grades spreadsheet. I tried.
Goodreader also cannot find and recognize the spreadsheet that I finally managed to download but cannot open, in Dropbox or Box or Evernote.
There is no way "to rename files" on the iPad because you simply cannot find them, as you can in the OS X finder. They are accessible only through apps, and apps have access only to a selected subset of files.
Perhaps Goodreader can rename the files it can recognize and open. This, it turns out, is not one of them.
Ladies and Gentlement, my iPad has a problem.
I'm sorry, it appears that GoodReader won't let you change a file's extension when it's renamed. I recall an older version of the app letting you change the file extension.
BTW, if you want to preview a comma-separated value file in Safari, you need to download the document with the *.csv extension. It will be formatted like a (very basic) spreadsheet.
Thank you. As I said elsewhere, this spreadsheet is so very wide that displaying it in Safari as data separated by commas in a .csv file does little good.
Seen as a .csv vile in Safari, no column lines up. It's all wrapped into a solid churn of numbers and commas that I can neither read nor save to a program capable of displaying it in columns.
I can live without solving this problem, but others who use the on-demand-data Web will also run into this difficulty on the iPad in its current state.