spec: add parameter postfixes

[Bilchreis]

Additions

• Restricted limits to scalar numeric types.

Remark

• This PR currently follows the variant where the _limits postfix is kept (i.e., target_limits remains valid, and _limits is treated as an allowed postfix / target_limits as a special case for backwards compatibility).

Open questions

(These may have been discussed already, but I couldn’t find/remember the answers in the minutes.)

• In an older meeting it was agreed to omit the _limits postfix. See minutes (09/2023): https://github.com/SampleEnvironment/SECoP/blob/master/minutes/2023-09-26_vidconf.rst#4d-issue-77-predefined-parameter-name-postfixes

  • The spec currently defines a specific target_limits parameter, but there is no corresponding HasLimits feature.

  • Should we deprecate target_limits and only allow the _min and _max postfixes?

    • This would not be backwards compatible.

  • Alternatively, should we introduce an additional _limits postfix and treat target_limits as a special case?

    • This would be backwards compatible.

• Do we allow postfixes only for predefined parameters, or also for custom parameters (those with a leading _)?

[markus-zolliker]

My opinion:
1c) we should allow _limits for the generic case
1a) we do not need a HasLimits feature, as it is covered by the generic postfix rule
1b) target_limits is therefore allowed
2) postfixes should also be allowed for custom parameters

[birkenfeld]

I agree with Markus' opinion.