Watson supports the following built in entities:

Entity Name	Binding Type
sys-currency	float
sys-date	DateTime
sys-location	string
sys-number	int or float
sys-percentage	int or float
sys-person	string
sys-time	DateTime

These entity assets are already created for you (in the System/Watson folder). You can use them in any of your intents just like other entities.

To get the value of a system entity at runtime, use the SystemValue property on the LexiconEntityMatch. Then call SystemValue.StringValue, SystemValue.FloatValue, etc.