Filter Apply Order

After proto 1.3.3 and above, the order that you apply filters to regions affects their behavior. Here is an example.

Let us start out with a basic filter that denies everything except TNT.

<all id="only-tnt">
    <material>tnt</material>
</all>

Now let us apply this filter to Region A, and also apply a filter to Region B that denies all blocks.

<apply region="region-a" block="only-tnt"/>
<apply region="region-b" block="never"/>

However, there is one slight complication. Region B is inside of Region A. So which filter will override the other? This is where the apply order comes in handy.

An overview of two sample regions and a depiction of two possible apply orders that affect how the regions operate.

The order that you put the <apply> tags can change the outcome when something gets filtered. In the previous example, the only-tnt filter would always override the never filter since it is above it. The apply for region B won't get checked since it overlaps completely with region A and region A never returns abstain.

If we changed the order of the filters:

<apply region="region-b" block="never"/>
<apply region="region-a" block="only-tnt"/>

Now you cannot place blocks in Region B, but outside of it in Region A you can only place TNT blocks.

Although this may not be an issue for many maps such as a Blitz map or a TDM, this is a crucial concept for many DTC/DTM/CTW maps that use the <void/> filter. Usually it's best to have the <void/> filter at the lowest priority (at the bottom of the list).