Every operation in MCA Selector starts with a selection, so the selection tools repay learning properly. This guide covers all of them: rectangle and brush selection, the chunk/region mode switch hidden in the zoom level, Invert and Clear, the Add and Subtraction modes, and saving selections to CSV so a careful selection never has to be built twice.
Two selection modes, decided by zoom
The most important selection “tool” is not a tool at all: it is the zoom level. Zoomed in, the map shows the chunk grid and you select individual chunks of 16×16 blocks. Zoomed out, the grid becomes regions of 32×32 chunks (512×512 blocks) and every click or drag selects whole regions. Switching happens automatically as you zoom — which is convenient, and also the number-one cause of accidental mass deletions. Build the habit: before any destructive operation, glance at the grid and say which unit you are selecting in. The delete chunks guide shows where this bites.
Rectangle and brush selection
- Click selects a single chunk (or region, at region zoom).
- Drag draws a rectangle — the natural way to mark a base, a city district or a cleanup zone.
- Shift + mouse paints with a brush: hold Shift and move across the map to add chunks in a free-form shape, which is how you trace coastlines, rivers and irregular build footprints that a rectangle would overshoot.
Invert and Clear
The Selection menu holds the two housekeeping operations. Invert flips the selection to everything except what you had — the foundation of the “keep this, delete the rest” workflows behind world pruning: select your bases carefully, invert, and the deletion candidate is everything else. Clear empties the selection so you can start fresh without reopening the world. After using Invert, re-check the map before deleting — deleting the inverse of your intent is the classic own goal.
Building selections up: Add and Subtraction modes
Complex selections are assembled, not drawn in one gesture. When you import a selection or apply a filter, you choose how the incoming chunks combine with what you already have:
| Mode | Effect |
|---|---|
| Add Selection | The incoming chunks are added to the current selection (the union). |
| Subtraction | The incoming chunks are removed from the current selection — carving protected or excluded shapes out of a bigger selection. Subtraction mode arrived in MCA Selector 2.7 and applies both to selection imports and to filters. |
A typical assembly: drag one big rectangle around a city, then subtract the rectangle of the one player’s plot that must not be touched, then add back a small outlying farm by hand. Three simple operations, one precise selection.
Saving selections to CSV
A selection disappears when you close the tool — unless you save it. Selection → Export selection writes the selection to a CSV file; Selection → Import selection reads one back, combining it with the current selection via the Add or Subtraction mode above. CSV selections earn their keep in three situations:
- Documentation — the CSV is the exact record of what a cleanup deleted; file it with your world backup.
- Repetition — recurring maintenance (monthly resets of a mining dimension, for example) reuses the same protected-area selection instead of redrawing it.
- Rehearsal — build the selection once, save it, then run the whole operation on a backup copy first; if the rehearsal passes, import the same CSV and run it on the real world. (The complete guide walks through this pattern.)
Selection discipline, in one list
- Confirm the zoom/mode unit before you start, and again before anything destructive.
- Prefer assembling (add + subtract) over heroic single drags.
- Export important selections to CSV before you use them.
- After Invert, look at the map — the highlighted area is what the next operation will touch.
Download MCA Selector 2.9
Everything in this guide works with the current release. Get the Windows installer, the cross-platform .jar, the macOS .dmg or the Linux .deb/.rpm from the MCA Selector download page — every button there points at the official GitHub release files and lists the SHA-256 checksum, with a clearly labelled site mirror as a fallback.
One last backup reminder: keep the copy of your world you made before editing until you have loaded the edited world in Minecraft and confirmed it looks right. Deletions and NBT changes in MCA Selector are permanent once applied.