[NEW FEATURE] MANAGE INSTRUMENT/SETTINGS --> deal with missing information for enum, numeric and boolean fields

[strambc]

Is your feature request related to a problem? Please describe.
It has been made clear by several users that sometimes a required value is not available for several reasons (including it is proprietary information, it cannot be located, etc.)

In addition to the user comments, it is essential to note that in all cases, it is helpful to make it explicit that this information has not been omitted inadvertently and to give a reason why it is missing.

For this purpose, similar to PIDINST, we propose to adopt the standard values for unknown information from DataCite.

If this field is of type STRING, this is not an issue, as the user can freely enter the appropriate controlled vocabulary term.

But what do you do when the field calls for a NUMERIC, ENUM or BOOLEAN type?

Describe the solution you'd like
It would be great if a field could be marked to indicate that the information is not available, even if it is ENUM, NUMERIC, or BOOLEAN in nature.

Alternatively:

For ENUM, the solution is to add default allowed values for missing information to all ENUM lists: in addition to a term for "Proprietary Information," allowed default values for missing information should be drawn from the DataCite schema.

For NUMERIC, an option would be to record "-1" in any field whose value is missing.
An alternative would be to create a code system to explain the reason why the information is missing:

Alternatives could be:

SIMPLE
-1. :prop proprietary information
-2. :unav value unavailable, possibly unknown
-3. other - empty value

COMPLEX
-1. :prop proprietary information
-2. :unac temporarily inaccessible
-3. :unal unallowed, suppressed intentionally
-4. :unap not applicable, makes no sense
-5. :unav value unavailable, possibly unknown
-6. :none never had a value, never will
-7. :null explicitly and meaningfully empty
-8. :tba to be assigned or announced later

For BOOLEAN
The solution could be making all BOOLEAN fields not MANDATORY.

Additional context
This is an issue that will come up very frequently when MMA is used in the real world.

[strambc]

The only way of doing it would be to change numerical fields to STRINGS

[strambc]

It is useful to make it explicit that this information has not been omitted inadvertently and to explain why it is missing.

For this purpose, similar to PIDINST, we propose to adopt the standard values for unknown information from DataCite).