A stopwatch with this complication can record “SPLIT-SECOND”. French translation is “rattrapante” which means something like “catch up”. It refers to a hand (for mecanical stopwatches), called “the rattrapante hand” which follows the hand of second and which is stopped by pressure on a command, while hand of second keeps running (thus the split-time can be registred without stopping the stopwatch). Rattrapante hand “catchs up” hand of second by a second pression on the specific command.
Here, a video showing a HEUER ref. 572 with SLIT-SECOND complication. Rattrapante hand is stopped at 36.8 seconds. It “catchs up” the hand of second by pressure on the left command.
Rattrapante is a word to design the mecanical way to record SPLIT-TIME. Quart stopwatch, like the ref. 1020 (microsplit), records SLIP-TIME in an electonical memory (see video below).
Additional informations about split function are also provided in this french Tag HEUER techical document, available : here.