450    unsigned int     nsp;               /* highest active entry+1 found so far */  member
895       dp->nsp = dp->tsp;  in push_opt()
1130       dp->nsp = dp->tsp;  in next_opt()
1165    assert(sp >= dp->nsp); /* nsp starts off zero */  in advance_opt()
1218          dp->nsp = sp+1U;  in advance_opt()
2016    dp->tsp = dp->nsp;  in write_png()
2017    dp->nsp = dp->csp = 0;  in write_png()
2158    if (dp->nsp/*next entry to change*/ <= log_depth)  in log_search()
2212    dp->nsp = 0;  in cp_one_file()
2223    if (dp->nsp > 0) /* interating over lists */  in cp_one_file()
2270       while (dp->nsp > 0);  in cp_one_file()