rem: struct keyfield *key = (struct keyfield *) xcalloc (1, sizeof *key); key->eword = -1;
add: struct keyfield *key = xzalloc (sizeof *key); key->eword = SIZE_MAX;
context: new_key (void){  struct keyfield *key = (struct keyfield *) xcalloc (1, sizeof *key);  key->eword = -1;  return key;}