descr_settlement_plan question

From what I understand, the way descr_settlement_plan works, is that for a specific slot, if I put a building in for a particular culture, then if that building exists, on the battlemap that building will be displayed as specified by the variant block it is inserted into.

Ex:

Code:

---

    slot slot_48_32_religious
    {
    <snip>
        variant
        {
            cultures
            {
                egyptian
            }
            buildings
            {
                temple_of_battle temple_of_battle_temple
                building_x building_x_level_y
            }
            ; no floor
            slot_upgrade_48x32_112x64_egyptian,    0,    0,    0,    0
            egyptian_temple,            0,    0,    0,    0
        }

---

If I add the bolded code into descr_settlement_plan, then if an egyptian culture builds level y of building x, and the settlement plan for the size of the settlement in which the building is built contains the slot_48_32_religious slot, then on the battlemap building_x_level_y should appear (assuming there is no temple_of_battle.

My question is, why do all the vanilla temples appear correctly on the battlemap (at least from city view), when only the temple_of_battle is listed anywhere in the settlement_plan files? I have also seen temple_of_governors and temple_of_healing show up in city view.

Note: In case is isn't clear, by city view, I mean viewing a settlement on the battlement through the settlement panel.