|Acid dissolve rate
Represents the absence of a particle. A theoretical particle with the ID "NONE" appears in the source code. If a transition changes the type of a particle to NONE, it is more simply explained as the particle disappearing. NONE can be drawn, but it acts as an eraser and will always replace existing particles.
Old TPT console commands also use "none" to represent a non-existing particle. Commands such as "!set type watr none" removes all WATR particles from the playfield.