digraph A {
    node [shape=plaintext];

    Weapon [shape=box];
    UnitAbility [shape=box];
    Unit [shape=box];
    Buff [shape=box];
    Effect [shape=box];

    Ability [label=<<table border="0" cellborder="1" cellspacing="0">
        <tr><td port="self" colspan="3">Ability</td></tr>
        <tr>
            <td port="Create">Build / Morph / Train</td>
            <td port="Other">Other</td>
            <td port="Research">Research</td>
        </tr>
     </table>>];

    Upgrade [shape=box];

    Requirement [label=<<table border="0" cellborder="1" cellspacing="0">
        <tr><td port="self" colspan="3">Requirement</td></tr>
        <tr>
            <td port="Building">BuildingExists / AddOn</td>
            <td port="Upgrade">Upgrade</td>
        </tr>
     </table>>];

    Ability:Other -> Effect [label = "causes"];
    Ability:Other -> Buff [label = "causes"];

    Ability:Create -> Unit [label = "produces"];
    Ability:Research -> Upgrade [label = "upgrades"];

    Requirement:Building -> Unit [headport="se"];
    Requirement:Upgrade -> Upgrade [headport="e"];

    Unit -> Unit [label = "normal_mode", tailport="w"];
    Unit -> Weapon [label = "has"];
    Unit -> UnitAbility [label = "has"];

    UnitAbility -> Requirement:self [label = "requires", headport="n"];
    UnitAbility -> Ability:self [label = "is"];

    {rank=same Unit Weapon}
    {rank=same UnitAbility Requirement}
    {rank=same Ability Upgrade}
}