eclipse jsp the function fn:escapeXml is undefined

I am beginning my first google app engine jsp project. I am following the tutorial for the guestbook from here: https://developers.google.com/appengine/docs/java/gettingstarted/introduction. I am on the datastore step ( https://developers.google.com/appengine/docs/java/gettingstarted/usingdatastore ) and have pasted in the code on that page directly into my project. The code compiles and works, but I get the red squiggly underlines under fn:escapeXml calls. I see that these are functions from a taglib, as explained here: http://www.tutorialspoint.com/jsp/jsp_standard_tag_library.htm . So, how do I make eclipse know what is going on and not think this is an error?