Step 2 of 4 in Files
Sample data, read from content-sdk
Its thumbnail
When Ana uploaded the English PDF, the tools made a second file from it: a picture of its first page, its thumbnail. Nobody draws or uploads a thumbnail.
Each PDF gets its own, so the Spanish thumbnail shows Lucía's first page.
Try it: open measuring-length-teach-book.pdf, and compare its first page with its thumbnail.
Loading the files kept for Length, Perimeter, and Area Teach Book
A thumbnail is made from its PDF, never the other way around, and a new PDF gets a new thumbnail. The tools keep both files.
