XLS and PDF explained
The pre-2007 Excel format is a binary structure limited to 65,536 rows and 256 columns — limits modern datasets routinely exceed.
PDF describes a page as a fixed arrangement of text, vector graphics and images. Unlike a word processor document, it is designed so the page looks identical everywhere — which is exactly why it is awkward to edit.
- Where XLS files come from
- Spreadsheets from Excel 2003 or earlier, and some legacy export systems.
- Where PDF is used
- Contracts, invoices, reports, forms, academic papers and scanned documents.