Add legal values definition and/or restriction on possible NoteRef attribute values

[Erik0x42]

• [ ] decide what values shall be allowed in NoteRef value field: GUID or simple/local Integer number of Note being referred to
• [ ] decide whether multiple NoteRefs shall be supported in one value field in one attribute element or by other mechanisms
• [ ] update Description of NoteRefs to define what values are expected, eg, "One or more references to drawing note by GUIDs, separated by comma"
• [ ] add RegEx constraint?
  • or just let description be the guide for implementation

Alternative:

• [ ] as an alternative to modifying the Norsok AML Library: document rules in a parallel "developer guideline and rules" document, for the purpose of reducing non-useful content in AML instance files (library is one thing, but anything added to AML library increases the size of all AML files)

[AlexTxen]

GUID of Note objects shall be used as NoteRef. Constraints to be added for NoteRef.