Who/What creates these messages in activity feed?

I’m using a customized thermostat device type and a custom thermostat app to change the temperature.

I see the following entries in the activity feed:

Date Source Type Name Value Displayed Text
2014-11-11 12:19:49.932 AM EST
8 minutes ago APP_COMMAND setCoolingSetpoint Basement Program Thermostat sent setCoolingSetpoint command to Basement Thermostat
2014-11-11 12:19:49.684 AM EST
8 minutes ago APP_COMMAND setHeatingSetpoint Basement Program Thermostat sent setHeatingSetpoint command to Basement Thermostat
2014-11-10 11:22:03.619 PM EST
1 hour ago DEVICE temperature 66.5 Basement Thermostat temperature is 66.5°F
2014-11-10 9:36:22.504 PM EST
3 hours ago DEVICE temperature 67.0 Basement Thermostat temperature is 67.0°F
2014-11-10 7:49:47.212 PM EST
5 hours ago DEVICE thermostatMode auto Basement Thermostat thermostat mode is auto
2014-11-10 7:49:47.212 PM EST
5 hours ago DEVICE thermostatSetpoint 63 Basement Thermostat thermostat setpoint is 63°F
2014-11-10 7:49:45.613 PM EST
5 hours ago DEVICE thermostatSetpoint 80 Basement Thermostat thermostat setpoint is 80°F

But NONE of the above are coming from my device type or app. So who is writing this to the activity feed?
If I need to write anything to the feed from the device type should I use

sendNotificationEvent( String )

or is there some other way to write to the feed from the device type and the app?

thanks.

Infact when I use that in the device type I get the following error:

12:41:14 AM: error groovy.lang.MissingMethodException: No signature of method: script1415684285914308354464.sendNotificationEvent() is applicable for argument types: (org.codehaus.groovy.runtime.GStringImpl) values: [Set Heating point to 61.0] @ line 341