Road cycling officials network stopwatch. This stopwatch records Marks and Splits and can send them to other members of your officiating crew using Twitter. The Tweets from the front of the race provide the location of the Marks allowing automatic Splits from devices following on the road which are running the app.
This app uses your GPS location and sends data including your location publicly through Twitter, so you need network and GPS capability on your device.
This app continues to use GPS running in the background which can dramatically decrease battery life. (A battery save option is available that reduces accuracy.)
A free Lite version is also available which will feed information to this full version. Sales of this app make the free version possible.
To get started, see the support website at http://321markapp.blogspot.com/p/setup.html then read Basics.