Hi Mike,
When you have a single entity or a collection of entities, the best practice would be to pass it through the outbound plug during navigation.
Since you have insisted "one, single parameter value", if it is a singlular value like integer, string etc you can as well pass it through a static public class attribute. You need to define a static public class attribute in any of your class(it can be the your source view controller class or of target view controller). Before navigation you need to set this static attribute at the source with the corresponding value. This would be easier and convenient when you want to pass a single value. But it is not recommended to go for many such static attributes. Also good care should be taken while using static attributes, since once set, it will hold the same value throughout a session, unless it is changed.
If you have many navigations to the same target view from different views, and if you need to pass the same attribute from these different source views, then you have to take care of setting this value in all these source views before navigating to the target view. Otherwise this attribute will hold the wrong value set by a different source view in the same session.
Thanks & Best Regards,
Leon