Index: server/ruleset.c
===================================================================
--- server/ruleset.c	(revisione 21272)
+++ server/ruleset.c	(copia locale)
@@ -1409,9 +1409,16 @@
   unit_type_iterate(u) {
     const int i = utype_index(u);
     struct unit_class *pclass;
+    struct requirement_vector *reqs;
     const char *sec_name = section_name(section_list_get(sec, i));
     const char *string;
 
+    reqs = lookup_req_list(file, sec_name, "reqs", utype_rule_name(u));
+    requirement_vector_copy(&u->reqs, reqs);
+
+    reqs = lookup_req_list(file, sec_name, "nreqs", utype_rule_name(u));
+    requirement_vector_copy(&u->nreqs, reqs);
+
     u->need_improvement = lookup_building(file, sec_name, "impr_req",
                                           LOG_ERROR, filename,
                                           rule_name(&u->name));
@@ -3889,6 +3896,7 @@
   int i;
 
   unit_type_iterate(u) {
+    int j;
     packet.id = utype_number(u);
     sz_strlcpy(packet.name, untranslated_name(&u->name));
     sz_strlcpy(packet.rule_name, rule_name(&u->name));
@@ -3904,6 +3912,16 @@
     packet.attack_strength = u->attack_strength;
     packet.defense_strength = u->defense_strength;
     packet.move_rate = u->move_rate;
+    j = 0;
+    requirement_vector_iterate(&u->reqs, preq) {
+      packet.reqs[j++] = *preq;
+    } requirement_vector_iterate_end;
+    packet.reqs_count = j;
+    j = 0;
+    requirement_vector_iterate(&u->nreqs, preq) {
+      packet.nreqs[j++] = *preq;
+    } requirement_vector_iterate_end;
+    packet.nreqs_count = j;
     packet.tech_requirement = u->require_advance
                               ? advance_number(u->require_advance) : -1;
     packet.impr_requirement = u->need_improvement
@@ -5022,6 +5040,15 @@
     }
   } improvement_iterate_end;
 
+  /* Units */
+  unit_type_iterate(putype) {
+    if (!sanity_check_req_nreq_vec(&putype->reqs, &putype->nreqs, -1,
+                                   utype_rule_name(putype))) {
+      ruleset_error(LOG_FATAL, "Units requirements are not sane!");
+      ok = FALSE;
+    }
+  } unit_type_iterate_end;
+
   /* Governments */
   governments_iterate(pgov) {
     if (!sanity_check_req_vec(&pgov->reqs, -1,
Index: common/unittype.c
===================================================================
--- common/unittype.c	(revisione 21272)
+++ common/unittype.c	(copia locale)
@@ -738,6 +738,20 @@
   return TRUE;
 }
 
+/****************************************************************************
+  Whether disaster can happen in given city.
+****************************************************************************/
+bool can_unit_happen(struct unit_type *punittype, 
+                     struct city *pcity)
+{
+  return are_reqs_active(city_owner(pcity), pcity, NULL, city_tile(pcity),
+                         NULL, NULL, NULL, &punittype->reqs,
+                         RPT_POSSIBLE)
+    && !are_reqs_active(city_owner(pcity), pcity, NULL, city_tile(pcity),
+                        NULL, NULL, NULL, &punittype->nreqs,
+                        RPT_CERTAIN);
+}
+
 /**************************************************************************
 Whether player can build given unit somewhere;
 returns FALSE if unit is obsolete.
@@ -965,6 +979,8 @@
   for (i = 0; i < ARRAY_SIZE(unit_types); i++) {
     unit_types[i].item_number = i;
     unit_types[i].veteran = NULL;
+    requirement_vector_init(&unit_types[i].reqs);
+    requirement_vector_init(&unit_types[i].nreqs);
   }
 }
 
@@ -987,6 +1003,8 @@
 {
   unit_type_iterate(punittype) {
     unit_type_free(punittype);
+    requirement_vector_free(&punittype->reqs);
+    requirement_vector_free(&punittype->nreqs);
   } unit_type_iterate_end;
 }
 
Index: common/unittype.h
===================================================================
--- common/unittype.h	(revisione 21272)
+++ common/unittype.h	(copia locale)
@@ -233,6 +233,8 @@
   struct advance *require_advance;	/* may be NULL */
   struct impr_type *need_improvement;	/* may be NULL */
   struct government *need_government;	/* may be NULL */
+  struct requirement_vector *reqs;
+  struct requirement_vector *nreqs;
 
   int vision_radius_sq;
   int transport_capacity;
@@ -386,6 +388,8 @@
 bool can_player_build_unit_now(const struct player *p,
 			       const struct unit_type *punittype);
 
+bool can_unit_happen(struct unit_type *punittype, struct city *pcity);
+
 #define utype_fuel(ptype) (ptype)->fuel
 
 /* Initialization and iteration */
@@ -398,12 +402,11 @@
 
 #define unit_type_iterate(_p)						\
 {									\
-  struct unit_type *_p = unit_type_array_first();			\
-  if (NULL != _p) {							\
-    for (; _p <= unit_type_array_last(); _p++) {
+  int _i_;                                                              \
+  for (_i_ = 0; _i_ < unit_type_array_last() ; _i_++) {                 \
+    struct unit_type *_p = utype_by_number(_i_);
 
 #define unit_type_iterate_end						\
-    }									\
   }									\
 }
 
Index: common/packets.def
===================================================================
--- common/packets.def	(revisione 21272)
+++ common/packets.def	(copia locale)
@@ -1170,6 +1170,10 @@
   TECH tech_requirement;
   UINT8 impr_requirement;
   GOVERNMENT gov_requirement;
+  UINT8 reqs_count;
+  REQUIREMENT reqs[MAX_NUM_REQS:reqs_count];
+  UINT8 nreqs_count;
+  REQUIREMENT nreqs[MAX_NUM_REQS:nreqs_count];
   UINT16 vision_radius_sq;
   UINT8 transport_capacity;
   UINT8 hp;
Index: client/packhand.c
===================================================================
--- client/packhand.c	(revisione 21272)
+++ client/packhand.c	(copia locale)
@@ -2858,6 +2858,17 @@
   u->require_advance    = advance_by_number(p->tech_requirement);
   u->need_improvement   = improvement_by_number(p->impr_requirement);
   u->need_government    = government_by_number(p->gov_requirement);
+
+  for (i = 0; i < p->reqs_count; i++) {
+    requirement_vector_append(&u->reqs, p->reqs[i]);
+  }
+  fc_assert(u->reqs.size == p->reqs_count);
+
+  for (i = 0; i < p->nreqs_count; i++) {
+    requirement_vector_append(&u->nreqs, p->nreqs[i]);
+  }
+  fc_assert(u->nreqs.size == p->nreqs_count);
+
   u->vision_radius_sq = p->vision_radius_sq;
   u->transport_capacity = p->transport_capacity;
   u->hp                 = p->hp;