12. CONCEALMENT Q&A

12.1 Concealment18 refers to a condition in which units are not seen by other units in play even though the omniscient player can see the physical presence of counters in a hex. To simulate an opposing unit's inability to see these units, a concealment counter ("?") is placed above such units so as to hide their true nature and provide them with several pertinent advantages. No unit can be concealed more than once at any one time, although one or more Dummy counters (12.11) can be placed atop a unit(s). Generally speaking "?" loss can occur due to an action performed while in the LOS of a Good Order enemy ground unit, whereas "?" gain can be denied while in the LOS of an unbroken enemy ground unit (which includes Dummies). Note the distinction: Good Order for "?" loss; unbroken (and Dummies) for denial of "?" gain. A vehicle that has neither an inherent crew, nor Passenger(s), nor Rider(s), is considered "broken" for "?" gain/loss purposes (i.e., such a vehicle can neither force loss of "?" nor block placement of "?").

12.11 KNOWN/DUMMY ENEMY UNIT: A unit or stack of units beneath a "?" is not a Known enemy unit and cannot be inspected by the opposing player. If a hex contains both concealed and unconcealed units, the unconcealed units must be placed on top. If a scenario allocates a number of "?" available for setup at the start of the scenario, those "?" can be placed atop each other to act as Dummies - thus giving the mistaken impression of a stack of real counters beneath a "?". A stack of Dummies containing no real unit may be moved as if it contains a real unit (even to the extent of being able to move with leader/Double Time MF bonuses), but it is removed if it moves without Assault Movement (or into Open Ground) in the LOS of a Good Order enemy as per 12.14. A ⅝" Dummy stack can claim to be an Emplaced Gun or a vehicle. Before announcing any mine attacks exposed by the movement of a stack topped by a "?", the DEFENDER may force the ATTACKER to reveal a non-Dummy unit in that stack to show that an actual force exists there. If he cannot, the Dummy stack is removed. Dummy stacks can be created only during initial setup and among OB-designated "?" reinforcements during their initial turn of entry. Multiple concealed units can combine into a concealed stack but must remove the top "?" counter from all but the original concealed stack. A concealed stack under a single "?" can split into separate stacks; each new stack is topped with its own newly created "?". A SW or other "non-unit" beneath a "?" cannot move unless carried by a non-Dummy unit. Q&A

12.12 PLACEMENT: The player setting up first in a scenario does so out of vision of his opponent, and after setting up his regular units may place only scenario OB-designated "?" at first - but only in Concealment Terrain (woods, rubble, building, brush, grain, marsh, or orchard). After his opponent sets up in the same manner, each unconcealed unit (of both sides) which is either out of the LOS of all unbroken enemy ground units within 16 hexes of it, or at ≤ 17 hexes from all of them, may have a "?" not designated by the OB placed on it [EXC: only one non-OB-designated "?" can be placed per stack of units]. Therefore, if one side begins with no forces on board, the other aide will be able to place "?" on all of its units after placing those units (before the opponent may look at the board). Thereafter, a "?" may be placed on top of any non-concealed Good Order unit before it enters the mapboard for the first time. During play (and in addition to all other restrictions; see 12.121) an Infantry unit can gain "?" only if it is non-concealed and in Good Order, and only at the end of its own Player Turn. A unit can never gain "?" while broken or berserk, because such a unit is not in Good Order. Q&A

12.121 CONCEALMENT LOSS/GAIN TABLE: The specific situations that allow "?" gain (or cause "?" loss) are given in the Concealment Table. To find if a particular non-concealed Good Order unit can gain "?" at the end of its Player Turn, determine: that unit's category in the Table, whether or not it is in the LOS of an unbroken enemy ground unit (and, if it is in such LOS, the range from the nearest such enemy having a LOS), and whether or not it occupies Concealment Terrain. Cross-index these facts to find the appropriate triangle; the letters in this triangle represent the Cases that list the specific situations in which that unit can gain "?". Not all the situations listed will necessarily apply to that unit in its present circumstances but, if one or more does apply, that unit is eligible for a "?". The Concealment Table always takes precedence over the body of the rules (e.g., an uncommon cause of "?" loss might be mentioned in the Concealment Table even though it is omitted from the rules proper for the sake of brevity). Q&A

EX: At the end of its Player Turn a non-concealed Infantry squad is out of the LOS of all unbroken enemy ground units and is in woods. Checking the Concealment Table, the applicable Case is found to be J. Therefore, the squad can gain "?" if it is in Good Order. If an unbroken enemy ground unit (including a Dummy stack; see "Unit" in Index) within 16 hexes of the squad had a LOS to it, it could not become concealed (Case "[NA]").

12.122 CONCEALMENT dr: There are two instances when a dr must be made to determine if "?" can be gained. These are:

Such a unit can receive a "?" only by rolling ≤ 5 on a Concealment Final dr. All such units in a stack check for concealment individually using a separate dr for each unit. The Concealment dr is subject to the following cumulative drm: Q&A

+XX is US#
+ZZ is Leadership of best leader in same Location unless alone (10.7)
+1Lax
-YY is TEM & Hindrance DRM of hex occupied (all hexside TEM are NA)
-1Stealthy

EX: At the end of their Player Turn, a Russian squad, HS, Hero, and 8-1 leader occupy an Open Ground Location out of the LOS of all unbroken German ground units but are still within 16 hexes of one. Case K of the Concealment Table thus applies. On an Original dr of 4 the squad fails to gain "?" (4 [dr] +3 [US#] -1 [Leadership] = not < 6). On an Original dr of 5 the HS fails to gain "?" (5 [dr] +2 [US#] -1 [Leadership] = not < 6), as would the leader (5 [dr] +1 [US#] = not < 6) since a leader can never modify his own DR. The Hero gains "?" automatically even on a dr of 6 (6 [dr] +1 [US#] -1 [Leadership] -1 [Stealthy] = 5 which is ≤ 5). If this same example were to occur in an Open Ground hex with a Dispersed Smoke counter, the highest Original dr gaining "?" in each case would be increased by two.

12.13 EFFECT: All fire and CC vs a concealed unit are halved as Area Fire [EXC: Residual FP, OBA, ordnance, Sniper, and minefield attacks]. Ordnance attacks apply the Case To Hit DRM instead of halving the FP of any resulting hit. The effects of Area Fire for concealment are cumulative with other causes of Area Fire. If a target Location contains both concealed and unconcealed units, any attack capable of affecting both types must be resolved once for each type, using a different FP column (or To Hit Numbers for ordnance) but the same DR. See also 12.16 and 12.2; for the effects of concealment in CC see 11.19 and 11.4-41.

EX: A concealed German 4-6-7 squad fires at a woods hex five hexes away containing a concealed 4-4-7 and an unconcealed 6-2-8; the 4-6-7's "?" is immediately lost (Case B of the Concealment Table). The German player rolls an Original 4 IFT DR which becomes a Final DR of 5 due to the TEM. The effect is a 1MC vs the 6-2-8 on the 4 FP column and a NMC vs the concealed 4-4-7 on the 2 FP column. Regardless of the outcome of the MC DR, the 4-4-7 loses its "?" (Case A of the Concealment Table). In the case of a hidden unit, the owner (or referee) must make these calculations mentally and reveal the unit if affected.

EX: A German 75mm gun fires at a woods hex containing a concealed 4-4-7 and an unconcealed 6-2-8 at seven hex range. The Final To Hit Number for the unconcealed unit is a 6 (7 [Basic To Hit Number] -1 [woods TEM] = 6), and for the concealed unit is a 4 (same calculation -2 [concealed target] = 4). If the German player rolls a 5 on his Final To Hit DR, he hits the unconcealed 6-2-8 and resolves that hit with a DR on the 12 column of the IFT, the concealed unit is not hit and does not undergo attack on the IFT. Had it been hit, it would have undergone an attack on the 12 column of the IFT, losing its "?" if the attack causes a "PTC" or better result.

12.14 REMOVAL: The specific situations that cause loss of "?" are listed in the Concealment Table, and are determined using the principles given in 12.121; note however that any LOS necessary to cause "?" loss must be from a Good Order (not just unbroken) enemy ground unit. When a unit loses concealment (see 12.31 for HIP loss) its "?" is removed immediately. When a concealed unit fails a MC or breaks or becomes Wounded/Reduced it loses its "?", regardless of the range to any enemy units in its LOS, or even if out of the LOS of all enemy units. A Dummy stack out of the LOS of all enemy ground units uses Morale Level of 7 when attacked, or when taking a PAATC (A12.41), or a Bombardment MC (C1.82). Any K/KIA result eliminates the stack. Whenever any of the following happens to a concealed unit while in the LOS of a Good Order enemy ground unit (regardless of range), it loses its "?": Q&A

A concealed unit's "?" is also lost immediately if it does any of the following in LOS of a Good Order enemy ground unit within 16 hexes (such potential LOS checks are free and require no attack or penalty for a blocked LOS):

This list is not all-encompassing; see the Concealment Table for other causes and conditions of "?" loss. A concealed Infantry unit may otherwise retain its concealment during Assault Movement or an advance even if it enters a non-Open Ground hex ADJACENT to a Good Order enemy, or even if it advances into CC (or an enemy unit advances into its Location). The owning player can voluntarily remove any concealment at any time during his or his opponent's Player Turn. If the only Good Order enemy ground unit in LOS is itself concealed when a concealed friendly unit makes a concealment-loss action (other than breaking or being Reduced/Wounded), that enemy unit must forfeit its "?" momentarily (to prove that it is not a Dummy) if it opts to force the friendly unit to lose his; the viewing unit's momentary forfeiture of concealment is instantly regained. The presence of a LOS Hindrance or beneficial defensive DRM (such as TEM and CA change DRM) along the LOS to a concealed unit does not prevent loss of its concealment. Loss of concealment by one unit does not necessarily cause loss of concealment to other units in the same Location.

EX: A concealed German 4-6-7, while at 12 hexes from (and in the LOS of) a Good Order Russian 4-4-7, uses Non-Assault Movement into a graveyard hex that contains a truck with a HS Passenger. The 4-6-7 loses its "?" (Case A of the Concealment Table), while the truck and its Passenger could not have even been concealed (Case H). A Russian HMG with leader direction later Final Fires at the graveyard hex at a range of 18 hexes; this attack has 1½ FP vs the Infantry 4-6-7 (6 [MG FP] x ½ [Long Range] x ½ [treated as Concealed target (Mandatory Fire Direction, 9.4)] = 1½), and vs the truck and HS Passenger it has 3 FP (since the concealment penalty of Mandatory Fire Direction only applies vs Infantry). If the 4-4-7 were not in Good Order (or were not present at all), the 4-6-7 would not lose its "?" when it moved (since the nearest Good Order enemy with a LOS to it would now be the Russians manning the HMG 18 hexes away, thus making Case E of the Concealment Table applicable for determining "?"-loss instead of Case A), while the truck and HS Passenger would still be unconcealed (Case H would still apply at ≥ 17 hexes) - so the MG's attack would still affect those units with 1½ FP and 3 FP respectively.

EX: Russian concealed squads are in 1N2 and P3. The Russian squad in N2 (even though presently in LOS of the German squad in M4) may move into O3 and P3 without losing its concealment because the hexes in which it expends those MF are not in LOS of a Good Order enemy ground unit within 16 hexes. If the building in N2 was instead a foxhole or pillbox containing the Russian squad, it would lose its "?" due to expending MF in Open Ground in N2 in LOS of a Good Order enemy ground unit, even if it uses Assault Movement to enter O3 (4.61); Case B of the Concealment Table. The Russian concealed squad in P3 can fire at the broken German squad in N4 without losing its "?" (except momentarily for verification) because there are no Good Order enemy ground units in LOS within 16 hexes. The concealed squad in N2 would have lost its concealment had it fired on the German in M4 (Case B) - even if that fire had broken or eliminated the German squad - because the German was in Good Order at the instant of attack. However, it may regain a "?" at the end of its Player Turn if it is in Good Order and there Is no unbroken enemy ground unit in LOS and within 16 hexes (Case J).

12.141 ACTIONS: Any other activity which a concealed unit engages in [EXC: operation of radio/field phone; taking a PAATC; attempted repair of a SW/Gun; Spotting; and application of a leadership modifier to another concealed unit's PAATC (EXC: 12.41)] causes loss of concealment if that unit is currently in the LOS and within 16 hexes of a Good Order enemy ground unit. Attempts to entrench, set a Fire, Deploy, Recombine, make a Sniper Check or PF/MOL/ATMM check, rally a broken unit, engage in Clearance attempts, change CA, apply a leadership modifier to anything other than a PAATC, or place SMOKE grenades are examples of actions that cause loss of concealment. A Snap Shot attack opportunity is not sufficient to cause the moving unit to lose its concealment unless the attack generates a "PTC" or better result. Q&A

12.15 DETECTION: Concealment can also be lost due to attempted enemy movement (not advance) into a concealed unit's Location. Whenever a non-berserk enemy infantry/non-charging Cavalry unit attempts to move into a Location containing a concealed unit during the MPh [EXC: Bypass; 12.151], the DEFENDER must immediately reveal at least one concealed unit in that Location and thereby force the moving unit back (even from a Wire Location) to the last Location occupied before entering his Location [EXC: units allowed to enter an enemy Location during the MPh; 4.14] where it will lose Concealment and end its MPh (unless it goes Berserk first) and is subject to possible Defensive First Fire attack (or, in the case of a routing unit, eliminated or captured for Failure to Rout; 10.533). If the ATTACKER is concealed, the DEFENDER can (before he reveals any unit) force him to momentarily reveal a non-Dummy unit in that stack; if the ATTACKER cannot, his Dummy stack is removed. The MF expended in attempting to move into the concealed unit's Location are still used, but are considered expended in the Location it is returned to; such re-entry causes any already-existing Residual FP in the returned-to Location to attack the returning unit - even if it had already attacked that unit in that phase. Similarly, a Unit forced back into a FFE or minefield Location is subject to FEE/minefield attack as it re-enters that Location. A unit forced back into a Wire Location is placed beneath the Wire counter. A unit forced back to a Depression Location is placed IN it - not in Crest status. A unit forced back to an entrenchment/shellhole Location can derive no TEM benefit therefrom vs any ensuing Defensive First Fire, although it can for any Defensive Final Fire or subsequent attacks. A Unit forced back to its previous Location is not subject to attack (even by a minefield or FEE) during its brief period in the previously-concealed unit's Location, nor can it be the subject of a Snap Shot from the firer's hex while attempting to enter the concealed unit's Location, but it is subject to Snap Shots/other First Fire attacks (see C.5C) when being returned to its previously occupied Location. Random Selection is used to determine which of multiple concealed units must lose their concealment, but all hidden Units in the Location must be placed on board beneath a "?" prior to that Random Selection. If the DEFENDER is unable to reveal a non-Dummy unit in that Location because there are none, all of his "?" in the Location are removed and the moving unit may continue its move from that Location without ever having been forced out of it. If the only concealed unit revealed is a SMC, the ATTACKER may, at his option, immediately attempt an Infantry OVR (4.15) if possible, thereby forcing the DEFENDER to immediately reveal another non-Dummy unit in the Location (if he has one). Q&A

12.151 BYPASS: A Unit concealed in woods/building terrain does not necessarily lose that Status due to an opposing Infantry unit using Bypass in that hex. The opposing Infantry unit must actually attempt to occupy the concealed unit's obstacle and Location (and this is not voluntarily done while using Bypass) to cause loss of concealment. However, should Defensive Fire, the presence of other unknown units In the planned exit hex, or other unforeseen circumstances force a Bypass Infantry Unit (or any other Infantry unit which legally ends its MPh in the same Location) to end its MPh prematurely in the Bypass Location with a concealed enemy unit, all concealment in that Location is lost. The previously concealed DEFENDING unit(s) may use TPBF against any units in the same Location and is also entitled to [EXC: if the targets are already pinned; 7.83] a -2 First Fire DRM for both FFNAM and FFMO unless the Bypass is through other than Open Ground (such as I9-H8 in 2I9). This FFMO DRM and the lack of TEM apply to units in an obstacle Location only if they were in the act of Bypass therein when First Fired upon (e.g., a berserk unit entering the same Location in non-Bypass mode would be subject only to FFNAM and the normal TEM of that Location). During Final Fire the moving units would be entitled to full TEM for the obstacle and may attack in turn during their AFPh (Area & TPBF) if they are able. Any survivors are not considered held in Melee until after the CCPh and are therefore able to rout away in the RtPh. Mark the stack with a CC counter to indicate that Melee rules do not yet apply. Any AFV using VBM in the hex can be attacked using Reaction Fire (D7.2). Q&A

12.152 SEARCHING: As each Good Order Infantry/Cavalry MMC, or moving stack that contains ≤ one MMC, ends its move it may attempt to reveal concealed enemy units (/Minefields; 12.33) in Accessible hexes by expending one additional MF in its present hex and making a Search dr, provided that all units making the attempt are neither Pinned nor using Assault Movement. Regardless of the outcome, that unit or moving stack is TI for the remainder of that Player Turn. The Final dr indicates the number of Accessible hexes of the ATTACKER's choice which the unit/stack may not Search. Such hexes may include those which the ATTACKER knows contain no hidden units (such as Open Ground or a just-traversed hex). This dr is modified as follows:

-1Per Stealthy Searching unit
-1Per HS equivalent > one HS Searching
+xLeadership factor of best participating leader
+1Per Lax or CX Searching unit (per each condition)

All Searched hexes (including all above-ground Locations in those hexes) automatically reveal their contents, including the presence of minefields (but not their type and strength) and Fortified Buildings. All enemy concealed units revealed lose their "?" (or if hidden are placed on board with a "?"). Q&A

12.153 MOPPING UP: During its PFPh, an armed Good Order Infantry MMC in a multi-hex/multi-level building (Note: each hex [not Location level] of a Rowhouse must be Mopped Up separately) that contains no unconcealed unbroken enemy unit, may declare that it is becoming TI so that it may secure the building, provided it is within two hexes of every ground level Location of that building which it or a friendly unit does not actually Control (26.11). If necessary, two or more units in different hexes may declare Mopping Up simultaneously (e.g., so that between them they can be within two hexes of every ground level Location of that building which their side does not Control). Any hidden enemy unit(s) in the building is immediately placed in view beneath a "?", and all enemy Dummies are removed. Other concealed units remain concealed. If no concealed enemy unit remains, the building is considered secured, all its Locations Controlled, and all broken enemy units therein immediately surrender to units of the ATTACKER's choice inside that building regardless of their proximity. Mopping Up can be attempted only once per building per Player Turn but can be attempted even if no stairwell is available to reach upper levels. A rubbled/Blazing building Location is not considered part of a building for Mopping-Up purposes. Once a side employs No-Quarter/Massacre (20.3-.4), it may no longer use Mopping Up. Q&A

EX: Two German squads occupy the ground level of F5 and F6 of building 1G6 which contains a broken Russian unit on level 1 of F6. The German squad in F5 declares Mopping Up in its PFPh and becomes TI. If no hidden enemy unit is found in the building, the broken Russian squad will have to surrender. However, a hidden Russian squad and a 9-1 leader are placed beneath a "?" in G6 so the broken unit does not surrender, and the Russian may make a dr to cause Search casualties with a -2 drm (-1 drm [leader] + -1 drm [extra HS] = -2). If he rolls an Original dr ≤ 3, the TI German squad will be Reduced to a HS.

12.154 SEARCH CASUALTIES: If a Location that is Searched/Mopped-Up contains an armed Good Order unit/minefield/Residual FP/HE FFE Blast Area, or if the DEFENDER has any Booby Trap capability (B28.9), the DEFENDER may make one Casualty dr per Search dr in an effort to cause casualties to the searching/Mopping-Up unit(s). This Casualty dr (which does not involve a "?" loss action) is in addition to, not in lieu of any attack made by the DEFENDING unit(s). A Final dr ≤ 1 causes Casualty Reduction to the Searching/Mopping-Up unit (or units if Random Selection results in a tie). This Casualty dr is modified as follows (based on the concealed status at the time of the Search dr):

-1Per Stealthy concealed DEFENDING unit
-1Per HS equivalent > one concealed DEFENDING HS
+xLeadership Factor of best concealed DEFENDING leader if not alone (10.7)
+1Per Lax concealed DEFENDING unit

12.16 RIGHT OF INSPECTION: If a stack is not concealed after play begins (2.9), the opposing player may inspect its contents - unless the stack is out of the LOS of all of his Good Order ground units, in which case he may only demand verification of action(s) taken. The required response to this demand is limited to showing only the information needed for verification. Since this would reveal Dummy stacks as soon as they move, players should simply not ask for verification of MF/MP expended by concealed moving units in exchange for not exceeding the MF capability of any concealed unit. Dummy stacks (not being Good Order) will not reveal hidden Fortifications (even after entering their Location of gaining LOS to them); players should adopt an honor system House Rule to balance the desire of the moving player to find hidden fortifications vs his desire to avoid revealing whether the stack is Good Order.

12.2 CONCEALED ⅝" COUNTERS: The rules of concealment apply equally to vehicles (and their PRC), Cavalry, horses, bicycles, and non-Emplaced Guns except that such concealment is lost immediately (regardless of range) whenever the unit is in the LOS of a Good Order enemy ground unit and not in Concealment Terrain (Case H of the Concealment Table), and is lost immediately if the unit moves (or is in Motion) in any way within 16 hexes and in the LOS of a Good Order enemy ground unit - even to change its CA within the same hex, regardless of the terrain it occupies (Cases B and D). A vehicle that sets up in a woods-road (or orchard-/brush-/grain- road) hex is considered to be in Concealment Terrain for the purposes of placing OB-designated "?" (12.12) and of using SSR-allowed HIP - but thereafter is considered to be on the road (B13.31) and thus in Open Ground to a clear LOS to it traced along the road. A concealed vehicle in the LOS of a Good Order enemy ground unit (regardless of range) loses its concealment if hit on a To Hit Table, or by at least a "PTC" result (or its corresponding DR, on the ★ Vehicle line or for OBA regardless of PRC vulnerability), or by an A-T Mine attack Immobilization result or better, on the IFT. Any Target Size DRM for a concealed vehicular/Gun target is not revealed until after the To Hit DR is made - and then only if it turns a miss into a hit (or vice versa). If a just-revealed Small Target Size (+1 or +2) DRM turns a hit into a miss, the vehicle/Gun does not lose its concealment. Only successfully firing a Smoke Dispenser - not just an attempt to do so - causes loss of that AFV's "?" (see D13.3). If a Gun, vehicle, Cavalry, horse, or bicycle (or SW) counter loses its hidden/concealed status (regardless of range) so does its manning Infantry or PRC, and vice versa. The BU, CE, TCA. HD status of a concealed vehicle may be secretly recorded at setup but must be revealed when the vehicle is unconcealed. See also 12.34. When a scenario OB gives a side a number of ½" "?" counters, the player may choose some/all ⅝" "?" counters instead. Q&A

12.3 HIDDEN INITIAL PLACEMENT (HIP): A SSR may allow HIP for one or more units. HIP is a form of concealment wherein a player may secretly record the location of his units in Concealment Terrain (including their CA for ⅝" ordnance weapons) by written side record rather than placing them on board beneath "?". Hidden Status is considered the equal of concealment except as otherwise specified. Solitaire players should substitute two "?" in a side's OB for each squad-capacity of HIP that a SSR grants that side. Q&A

12.31 Once revealed, a hidden unit may never regain hidden status, although it can gain concealed status. A revealed hidden unit is totally discovered; it is not placed on board beneath a "?" unless specifically stated by a rule covering that particular situation (e.g., 11.19, 12.15, .152, .153, .32, .34).

12.32 Hidden units may not move (even within their hex or to change a CA) or advance and remain hidden. If a hidden unit is to move/advance it must first be placed on the mapboard beneath a "?"; normal concealment rules then apply to its activity. A hidden unit may sacrifice its hidden status and become concealed to prevent an opposing unit in LOS from gaining concealment or to affect an enemy unit during that unit's RtPh.

12.33 FORTIFICATIONS: Fortifications in Concealment Terrain may always set up hidden and remain hidden until use of its protective TEM is claimed, or a unit therein loses its concealment, or a Good Order enemy ground unit gains a LOS to its Location and is within 16 hexes. [EXC to all: Minefields; B28.1.] Fortifications set up in non-Concealment Terrain are treated as if set up in Concealment Terrain [EXC: they also lose their HIP status due to enemy LOS regardless of range]. The presence (but not the actual strength) of minefields can he discovered by a successful Search (12.152). A unit entering/exiting a hidden Fortification (including Wire but not Panjis) pays no MF/MP to do so, provided that Fortification remains hidden. Hidden Fortifications revealed by LOS during setup are placed onboard just prior to placing non-OB "?". Q&A

12.34 HIDDEN GUNS: An Emplaced (C11.2) non-vehicular Gun may always use HIP if it sets up (i.e., starts the scenario) in Concealment Terrain, even if in the LOS of an enemy unit. An Emplaced Gun may also always use HIP if not in Concealment Terrain, provided it sets up out of the LOS of all enemy ground units - but must be placed onboard under a "?" as soon as a Good Order enemy ground unit has a LOS to it regardless of range. An Emplaced hidden/concealed Gun that fires is revealed if the colored dr of its Original TH DR is ≥ 5 and the nearest Good Order enemy ground Unit with a LOS to it is within 16 hexes, or if that dr is a 6 and the nearest such unit with a LOS to it is at ≥ 17 hexes; otherwise that Gun is placed (or remains) beneath a "?" [EXC: if hidden it retains HIP if no Good Order enemy ground unit has a LOS to it when it fires at other than a FB/DB (E7.); a RCL (C12.22), or a Gun firing at-zero-range/using-IFE, is always revealed if it fires while in the LOS of any Good Order enemy ground unit]. See 12.2 for the HIP/"?" loss-gain relationship between a Gun and its manning Infantry. Q&A

12.4 VEHICULAR MOVEMENT THROUGH CONCEALMENT: The presence of any concealed unit(s) in a Location does not itself prevent an enemy vehicle from entering that Location.

12.41 OVR: Should an "unbroken" (12.1) vehicle enter a concealed enemy's Location without using Bypass or a woods-road, all concealed enemy Personnel [EXC: those exempt from PAATC] in that Location must instantly either be revealed voluntarily (12.14) or take one combined PAATC (1PAATC if any of them are Inexperienced) using the lowest current Morale Level among them, modified by the DRM of the best unpinned friendly Good Order leader present. A Dummy stack takes its PAATC with a Morale Level of 7. If that PAATC is failed, all those subjected to it are immediately pinned and revealed. If the Location contained no Known enemy unit when the vehicle entered it, OVR expenditure is NA until the combined PAATC (if any) has been resolved, after which the vehicle may conduct an OVR if able to (D7.1). In all cases, if the PAATC is passed, those concealed units remain concealed and thus can be OVR only as Area Fire; if no OVR is made, the vehicle it still subject to attack (including CC Reaction Fire: D7.2) by any eligible unit(s) in the normal manner. Q&A

12.42 BYPASS: A vehicle entering a concealed enemy's Location using Bypass may not attempt an OVR as part of that entry or even be informed of any hidden unit(s) therein. Concealed unit(s) in the Location are revealed due to the vehicle's presence only voluntarily, or if the vehicle/its-Passenger(s)/Rider(s) end it's MPh in that Location [EXC: a "broken" vehicle cannot cause concealment loss; 12.1]. Since a Bypassing vehicle occupies only the hex containing the terrain being Bypassed (C.5C), it has no effect on the concealment of any unit(s) in an adjacent hex.