usr/src/cmd/lisp/catchframe.h

struct catchfr {                /* catch and errset frame */
    struct catchfr *link;       /* link to next catchframe */
           lispval flag;                /* Do we print ?  */
           lispval labl;        /* label caught at this point  */
    struct nament *svbnp;       /* saved bnp */
           lispval retenv[10];  /* reset environment */
           lispval rs[4];       /* regis 6-11 and 13 */
       lispval (*retadr)();     /* address to continue execution */
};