compound_data_type Interface

# `compound_data_type` Interface

A data-policy indicating that an associative container has multiple mapping levels.

1. `data_type.hpp`
2. Template parameters.
3. Public Types and Constants:
   1. General definitions.

## Template parameters.

Parameter | Description | Default Value
    Cntnr
| (Associative) container type to which every key in the container maps. | -

## General definitions.

Type | Definition | Description
    cntnr
    Cntnr
| The type of container which is the actual data type.