Header and Parameter in header ambiguity

[pmerson]

The Components object has:

• parameters - collection of Parameter objects
• headers - collection of Header objects

However, a Parameter can be a header (when in == "header").
This inherent ambiguity creates confusion when one tries to create a global/group customization.

Can the ambiguity be removed (maybe deprecating the Header object or the "header" location of Parameter)?
If not, when should I declare a header as a Parameter and when should I declare it as a Header? The answer to this last question is direly needed in the documentation.