latch3 is another automation recorder similar to latch2. However, it is conceptually different from latch2 in that its timing is tightly coupled to master. The duration of an automation is defined prior to recording. Recording starts only at every n=length steps. Events are recorded in relation to current master time, so changing master tempo also affects playback of automation recordings. Also, it is not limited to single-number parameters, but records any events that share the same OSC address. This involves the danger of breaking a session when not handled carefully. Due to the fact of being timing-wise coupled to master, latch3 does not work without it.
Before you record, set the desired length (with number that defaults to 16). Then hit the record button (red circle). A pink cursor indicates the time until actual recording starts. By touching any controller in netpd, you might already set parameter to be recorded without recording a value yet. As soon as the master clock reaches a multiple of the predefined length, the actual recording starts and the cursor turns red. Changes to the parameter are recorded now, until the length is reached and recording stops automatically.