Empty values
The most common surprise. In most places an empty field does not mean "do nothing" — it means "write nothing", which clears the parameter.
| Where | Empty field means |
|---|---|
| Set Value, Value | Clears the target |
| Room Data, Space Data, Area Data, Level, Nearest Grids — the "if not found" field (e.g. If in no room) | Clears the target of every element nothing was found for |
| Map Values — If no row matches | You choose: Write text, Clear or Leave unchanged (the default) |
| Map Values — an empty cell in a table row | Leaves that target unchanged; <clear> in the cell erases it |
The reasoning: a value read from where an element stands becomes wrong the moment the element is no longer there, so an old room number is better erased than kept. Map Values is the exception because a missing row usually means "not mine" — a value somebody typed by hand.
To protect existing values, tick Only if empty. It is in More settings of Set Value, and the Executor offers it per operation in its list just before you run.