the invisible book

We use RFID in the library. Patrons use self-checkout machines. An RFID chip in the book (or DVD or CD or whatever) is read by the machine, which then adds the item to the patron's checkout record.

The machines are temperamental. They seem to confuse themselves. This is one of the weirder quirks: Let's say you've stepped up to the machine. The machine features a helpful wide shelf for holding items for checkout. You lay your book there. You pass your library card under the laser scanner and the machine identifies you. Great! Now you watch the animation on the screen that demonstrates the proper method for checkout. The animation has disembodied hands laying a stack of books down on the nice convenient shelf on which you've already laid that one book you were planning to take home.

You wait.

Nothing happens.

You lift the book and lay it down again, imitating that animation that keeps repeating itself. Your book is not getting checked out. What's wrong?

What's wrong is that you placed the book on that helpful wide open shelf before you scanned your card. Anything that is sitting on that beckoning convenient shelf when you start the process seems to be invisible to the checkout machine. What you now have to do is remove your book, put it somewhere next to the machine or hold it in your hand out of the machine's RFID range, and restart the process. Now it works. Usually.

Except when it doesn't. Then you have to take the book to your helpful human who will use his or her staff checkout machine.

Most people are good at using the self-checkout machines. And most the time the self-checkout machines do their job the way they are supposed to. Once in awhile someone gets a techno-gee-whiz glow from the thrill of interfacing with the 21st century. Other times we see crinkly faces & curses. But mostly it's okay. We all get through it - patrons, library workers, and RFID machines.