The prerequisite is in the itemtype, not the tech. CoreItems.xml
<GameItemType InternalName="QuestMap">
<DisplayName>Quest Map</DisplayName>
<Description>These maps can be used as clues to unique opportunities in the world.</Description>
<ShopValue>100</ShopValue>
<GameModifier>
<ModType>Map</ModType>
<Attribute>CreateQuestNearTile</Attribute>
<BoolVal1>1</BoolVal1>
<Value>-1</Value>
<Radius>-1</Radius>
<Provides>Spawns a new quest</Provides>
</GameModifier>
<IsAvailableForSovereignCustomization>0</IsAvailableForSovereignCustomization>
<Likelihood>200</Likelihood>
<RarityDisplay>Uncommon</RarityDisplay>
<HeroOnly>1</HeroOnly>
<IsAvailableForUnitDesign>0</IsAvailableForUnitDesign>
<IsUsable>1</IsUsable>
<Prereq>
<Type>AbilityBonusOption</Type>
<Attribute>Wanderlust</Attribute>
<Target>Player</Target>
</Prereq>
<Prereq>
<Type>Tech</Type>
<Attribute>Breons_Letters</Attribute>
</Prereq>
<ArtDef>QuestMap_ArtDef</ArtDef>
<GameItemTypeArtDef InternalName="QuestMap_ArtDef">
<GameItemTypeModelPack InternalName="QuestMap_Default">
<IconFile>Parchment1.png</IconFile>
<TintR>0</TintR>
<TintG>0</TintG>
<TintB>0</TintB>
<GameItemTypeModel>
</GameItemTypeModel>
</GameItemTypeModelPack>
</GameItemTypeArtDef>
</GameItemType>
This is mostly how it works (children attach to their parents rather than parents attaching to their children), with some small exceptions such as unlockable skills from wearing items.