Template Functional Requirements

HL7 V3 Templates maintain a set of functional requirements. What is the list of functional requirements required of Templates for use in HL7?

Template Assertions

Static assertions

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• A template can constrain the cardinality of a clone’s association.
• A template can constrain the cardinality of a clone’s attribute.
• A template can constrain the allowable date/time values in a date/time field.
• A template can constrain any attribute value to be a subset of those values legally permissible in the specification being constrained.
• A template can constrain the range of allowable date/time values for attributes valued by date/time data types.
• A template can constrain the range of allowable code values for attributes valued by terminology concepts.
• A template can constrain the range of allowable numbers for attributes valued by numbers.
• A template can express a regular expression constraint on attributes valued by strings.
• A template can constrain any data type component, including recursively-nested components.
• A template can constrain the range of allowable values of a clone’s attribute.
• All additional constraints that can be expressed in a normative specification (including all the columns in an HMD) can be further constrained in a template.

Co-occurrence Assertions

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• The value of one field can be constrained based on the value of another field.
  Example: If fieldOne is “X”, then fieldTwo’s value must be “A”.
  

• Chronological assertions can constrain the date/time value of one field based on the date/time of another field.
  Example: The start time for fieldOne is (earlier | later | equal to) the start time of fieldTwo.

• Numeric comparison assertions can constrain the numeric value of one field based on the value of another field.
  Example: The value of fieldOne is (equal to | less than | greater than) the value of fieldTwo.

• Numeric operation assertions can constrain the numeric value of one field based on a numeric operator applied to the value of another field or constant.
  Example: The value of fieldOne is (equal to | less than | greater than) the value of fieldTwo (plus 7 | divided by 27).

• String comparison assertions can constrain the string value of one field based on the value of another field.
  Example: The string value of fieldOne is contained in the value of fieldTwo.

• Any constraint a template and constituent archetypes can make can be made dependent on the value expressed in one or more other fields. For instance, in addition to constraining the cardinality of an association, a template and constituent archetypes can constrain the cardinality based on the value in a particular field.
  Example: If ((fieldOne is “X” or “Y”) OR (fieldTwo is “ABC”)) then ((a nested act relationship under Observation is required) AND (fieldThree in the nested act has a value of “A” or “B” or “C”) AND (fieldThree in the nested act cannot be NULL)).

Containment Assertions

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• Data descendant assertions can constrain allowable depth at which one component is nested within another component.
  Example: The vital-signs section must be (a direct child of | some descendant of | less than a depth of X from) the physical-exam section.

• Items in a template and constituent archetypes can be “ordered” or “unordered”. In an ordered template and archetype, the order of the stated assertions is important. In an unordered template and archetype, the order is not important.
  Example: Assertion One: There is a nested act under observationOne that has an observation.cd for “hemoglobin”. Assertion Two: There is a nested act under observationOne that has an observation.cd for “hematocrit. If the template and constituent archetypes are “ordered”, the “hemoglobin” must come before the “hematocrit”. If the template and constituent archetypes is “unordered” the “hemoglobin” can come before or after the “hematocrit”.

Logic Assertions

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• Logical operators can be applied to a set of assertions to indicate which assertions in the set must be true or false. Example: (All | at least X | at most X | exactly X) of the assertions contained in this set must be (true | false).