Z:gnu-www-ja-w3c-patent--e1bc1f-The problem comes from the =26ld/en

The problem comes from the &ldquo;field of use&rdquo; restrictions that patent holders are allowed to put in their royalty-free patent licenses. Such restrictions say that you are allowed to practice the patented idea, but only for implementing the standard precisely as specified &mdash; not in any other way. Thus, if you change the code to depart from the spec even slightly, the patent license no longer protects you from against being sued for infringing the patent.