As the title says...

Lets look at: (vanilla Chernarus snippet)

    <type name="Mag_AK101_30Rnd">
        <nominal>16</nominal>
        <lifetime>28800</lifetime>
        <restock>0</restock>
        <min>13</min>
        <quantmin>5</quantmin>
        <quantmax>50</quantmax>
        <cost>100</cost>
        <flags count_in_cargo="0" count_in_hoarder="0" count_in_map="1" count_in_player="0" crafted="0" deloot="1"/>
        <category name="weapons"/>
        <usage name="Military"/>
        <value name="Tier3"/>
        <value name="Tier4"/>
    </type>

This item clearly should spawn only on Helicrash, Military convo, etc. that are located in Tier3/4 parts of the map.
To my konwledge this is not the case, and they can spawn at any Military dynamic event proto.

I will consider this one an additional info:

I have NOT tested this recently, but when I ran my server I was unable to split dynamic loot through the tier flags. They spawned at any matching USAGE event

If a loot set to be a DynamicLoot, has tier values set, it should spawn only on certain - geographically matching - events.