DiagCatType can be optional

[oliveregger]

Can we use Coding without system? DiagCatType is optional

                                <Condition>
                                    <id value="Diagnosis"/>//

                                    <code>
                                        <coding>
                                            <!-- 2.9.3 Katalogtyp (DiagCatType) -->
                                            <!-- TBD -->
                                            <system value="http://www.example.com/CHOP"/>
                                            <!-- 2.9.1 Diagnosecode (DiagCode) -->
                                            <code value="99.99"/>
                                        </coding>
                                    </code>

[ziegm]

FHIR spec (Coding):
Coding.system = 0..1

In some cases, the system might not be known - only the code is known. In this case, no useful processing of the code may be performed unless the system can be safely inferred by the context. This practice should be avoided where possible, as information sharing in a wider context is very likely to arise eventually, and codes cannot be used in the absence of a known system.

Validation with IG Publisher:
warning: A code with no system has no defined meaning. A system should be provided

CH ALIS: The system is currently defined with cardinality 0..1 in the condition profile.