Ok. The thing with trackbacks is, that they're used only for spam! Hate it.
Seven years ago it was said that 53% of all pings is spam. Today I'd say 100% of all pings is spam or sping. There is no point in allowing pings or trackbacks.
My blog software is Serendipity. It has following instructions for removing trackback links. Unfortunately the platform is well known and simply removing the links from HTML doesn't do the trick. The "official" word from Serendipity authors is to start using a plugin for managing spam trackbacks. Ok, since all of it is spam why bother!