we need a metadata section in service template to contain service specific parameters
such as in NFV, we need

tosca_definitions _version: # Required TOSCA Definitions version string
tosca_default_namespace : # Optional. default namespace (schema, types version)
template_name: # Optional name of this service template
template_author: # Optional author of this service template
template_version: # Optional version of this service template
description: example for a NSD.
service_properties:
ID: # ID of this Network Service Descriptor
vendor: # Provider or vendor of the Network Service
version: # Version of the Network Service Descriptor
service_properties here defines the NFV specific properties, but in general, we need a common secition called metedata in service template to contain any service specific properties.