NROFFCHARS
if (i + _SPECCHAR_ST >= NROFFCHARS) {
c_isalnum = NROFFCHARS;
char xchname[4 * (NROFFCHARS-_SPECCHAR_ST)]; /* hy, em, etc. */
short xchtab[NROFFCHARS-_SPECCHAR_ST]; /* indexes into chname[] */
char *codetab[NROFFCHARS-_SPECCHAR_ST];
char width[NROFFCHARS];