hl7 fhir - Binding multiple value sets to a single extension element -

i'm wondering if there way bind multiple value sets single extension element in fhir.

here's example of i'm trying achieve:

<structuredefinition xmlns="http://hl7.org/fhir">   ...   <snapshot>     ...     <element>       <path value="extension.valuecode"/>       ...       <type>         <code value="code"/>       </type>       <binding>         <strength value="required"/>         <valueseturi value="http://stelar.org/valueset/const-yesno"/>       </binding>       <binding>         <strength value="required"/>         <valueseturi value="http://stelar.org/valueset/missingdata"/>       </binding>     </element>     ...   </snapshot>   ... </structuredefinition> 

my reason wanting bind multiple i'm porting data on legacy system in coded values can either come value set represents collected data, or separate value set represents missing data. reason split more known why data missing.

i don't want go create composite value set every combination of missing value set, , various other value sets if possible, minimise reuseability of value domains.

i'm not sure if i'm getting syntax wrong, can't find mention of multiple bindings in documentation, , upload file in above (or below format) simplifier, renders 1 bound domain, makes me think accepting last child.

  <binding>     <strength value="required"/>     <valueseturi value="http://stelar.org/valueset/const-yesno"/>     <valueseturi value="http://stelar.org/valueset/missingdata"/>   </binding> 

is there way bind multiple value sets? there better way of handling missing data in fhir?

see http://build.fhir.org/elementdefinition-definitions.html#elementdefinition.binding - binding can appear once. creating multiple bindings has number of practical consequences, expectation you'll define single value set imports other 2 value sets might include. note create contained value set in structure definition imports 2 actual value sets, since has no real existence or meaning outside structure definition

we discussing use cases multiple bindings right - it's complicated. if there's more 1 binding, 'and' or 'or'?