Invariants not implemented in class DvText

[Sergio Miranda Freire]

The following invariants are not implemented:

Mappings_valid: mappings /= void implies not mappings.is_empty
Formatting_valid: formatting /= void implies not formatting.is_empty
Value_valid: value /= void and then not value.is_empty and then not (value.has(CR) or value.has(LF))
                   Maybe this is the reason why class OPENEHR_DEFINITIONS was created.

Language_valid: language /= Void implies code_set(Code_set_id_languages).has_code(language)
Encoding_valid: encoding /= Void implies code_set(Code_set_id_character_sets).has_code(encoding)

Here we will need to use openehr terminology.

Maybe it is interesting to implement a representation method for this class.