TMSS-215: added doc string

SAS/TMSS/src/tmss/tmssapp/models/specification.py

@@ -233,6 +233,10 @@ class DefaultGeneratorTemplate(BasicCommon):
 
 
 class SchedulingUnitObservingStrategyTemplate(NamedCommon):
+    '''
+    A SchedulingUnitObservingStrategyTemplate is a template in the sense that it serves as a template to fill in json data objects conform its referred scheduling_unit_template.
+    It is however not derived from the (abstract) Template super-class, because the Template super class is for JSON schemas, not JSON data objects.
+    '''
     version = CharField(max_length=128, help_text='Version of this template (with respect to other templates of the same name).')
     template = JSONField(null=False, help_text='JSON-data compliant with the JSON-schema in the scheduling_unit_template. '
                                                'This observation strategy template like a predefined recipe with all the correct settings, and defines which parameters the user can alter.')