lib/texinputs/isabelle.sty

--- a/lib/texinputs/isabelle.sty	Wed Dec 06 21:01:01 2017 +0100
+++ b/lib/texinputs/isabelle.sty	Wed Dec 06 21:30:26 2017 +0100
@@ -259,5 +259,7 @@
 \isakeeptag{ML}
 \isakeeptag{visible}
 \isadroptag{invisible}
+\isakeeptag{important}
+\isakeeptag{unimportant}
 
 \IfFileExists{isabelletags.sty}{\usepackage{isabelletags}}{}