Hello again, For source code blocks with long header lines, org allows the use of the #+header: or #+headers: alternative for specifying these. Attached is an example. The problem is that using these seems to cause fontification to stop working and, unfortunately in a non-reproducible manner, also causes some problems with C-c' working for allowing me to edit the code in a code specific mode. Fontification works just fine if the header arguments are on the #+begin_src line, however.