NSO
extern int ifl[NSO];
extern char cfname[NSO+1][NS];
if (skip() || !getname() || ((i = open(nextf, 0)) < 0) || (ifi >= NSO)) {
filep ipl[NSO];
long offl[NSO];
char cfname[NSO+1][NS]; /*file name stack*/
int cfline[NSO]; /*input line count stack*/
int ifl[NSO];