Talk:Dev:Semantic Constraints

Discussion March 2020

Initial question: what are semcons and what are no semcons?

Questions

• Definition
  • Suggestion:
    A semantic constraint is a constraint that cannot be implemented in an XSD.
  • What is obviously a semcon?
  • What is obviously not a semcon?
    • Element semantics and attribute semantics - otherwise every element semantics and attribute semantics would be a semcon (although it is potentially dangerous to put the dead weight under <vehicle>@nettoWeight and the load capacity under <vehicle>@tareWeight).
    • Intentions (about the function of a certain Element/Attribute)
    • Recommendations
    • Best Practices
    • Conclusions from syntactic constraints and/or element/attribute semantics
    • Explanations of semantic constraints
  • Cf. [1]→[2]
• Goals
  • Interoperability?
  • Do they apply to the developer or the user?
  • Who can control/guarantee compliance?
• Design
  • Allow/deny the recycling of discarded numbers?

Creating semantic constraints

• Suggestion and Discussion
  • either in the railML^® Forum
  • or in a railML^® working group
    →in this case the working group must present their discussion result in the forum and grant a term for discussion there
• Enter the semcon with status proposed into the wiki
• If there are no objections, the semcon becomes accepted after a certain term (6 weeks)
• In case of objections the working group decides

Design guidelines

• Use the template with all mandatory arguments
  The template must be extended with an argument to link to the discussion as to grant that the proposal is preceded by a discussion
• Implement a seperate semcon for every rule
• Record on Dev:Semantic_Constraints/table
• numbering according to Dev:Semantic_Constraints/table

Distinctions within element documentations

• Position of times in the XML-Tree: straightforward from the schema
• Multiplicity: straightforward from the schema
• Semantics: Only the intention. No rules or explanations. Concise remarks like “not to be confused with” are allowed, if they explain the intention
• Attributes: No rules or explanations. Concise remarks like “not to be confused with” are allowed, if they explain the intention
• Syntactic constraints: straightforward from the schema
• semantic constraints: compare above
• Best Practice Examples: for instance national rules and peculiarities; Code examples
• Open Issues: open discussions and unsolved problems
• Notes: Anything that does not fit into other paragraphs

Where can you comment on the semantics in wiki3?