What characters are special in an nginx map instruction?

I'm moving a site to a new structure and want to use nginx's map to map old URLs to their new locations. For simple cases that works like a charm, but I have trouble with some values. This is what I tried:

   /old/page1.htm /new/info.html;

works like a charm. Then I tries these:

/stw/wisselblog.nsf/0485b0c9032c281ac1257b10001decbb/839ed94b2337e5634825737600305ecf/entryrich/0.204?openelement&fieldelemformat=gif /blog/images/rtimg/23.gif;

in the variation above and then with backslash only on the & ? and = and any combination of backslahes before the three.

none of these works. I get the error: nginx: [emerg] conflicting parameter.

In case you think the first URL is made up, look for yourself

What do I miss?

Update: the mapping isn't regex capable since the file names change.