OntoDL Statement: define

Syntax

---

DefinitionStatement	:=	define TypeName ObjectName DefinitionBody
ObjectName	:=	Name
DefinitionBody	:=	{ FullDefinition * }
	|	= QualifiedConcept
	|	= InternalReference
Fulldefinition	:=	DefineStatement
	|	DefaultStatement
	|	SetStatement
	|	PredicateStatement
	|	SetAsTableStatement		Must be formatted as 2-column MS Word table using style "OntoDL"
SetAsTableStatement	:=	PropertyName ($? Text		The prefix "($" advises the OntoDL interpreter to consider the provided text as a string (which will not be further processed)
	|	PropertyName InternalReference
PropertyName	:=	Name

---

Description

The define statement is used for introducing a new named object to OntoDL. Upon introduction a new object is given a name and assigned a type. These properties are fixed through the define statement and cannot be changed afterwards. The immediate binding of a new object to a type is important because not only the object's behavior but even the way you may use that object within OntoDL is determined by its type. The table below lists, how you may further define objects of the defined OntoDL types.

type	definiton	specific behavior
codesystem	full definition	exported as a FHIR ValueSet resource (or FHIR STU-3 Codesystem resource)
system	full definition, internal reference	ID and version information goes into references to external code systems
concept	full definition, internal reference, qualified concept	exported as part of a code system unless given a silent name
predicate	full definition	exported as concept reference unless given a silent name
property	full definition	exported as string reference unless given a silent name

Full Definition

The OntoDL full definition syntax is applicable to all types of objects. A full definition consists of a sequence of OnotDL statements within a definition scope that is confided by curly brackets. A full definition may be empty; in that case it only consists of a pair of curly brackets.

The example below shows a full definion of a code system "animals" that consists of different kinds of OntoDL statements to define the semantics and content of the code system. The included concept "mouse" is not further defined as its definition scope is empty.

define codesystem animals {
  default Language = en
  set me.URI = (http://test.com/animals)
  define concept mouse { }
  define concept elephant {
    --(bigger than)--> mouse
  }
}

A special way for setting property values to an object is to place a MS Word table with two columns into the definition scope. This table holds the name of the property in the first column and the property value in the second column. You may advise the OntoDL interpreter to consider a property value as a string by prefixing it with "($".

---

Style Sheet		Text		Comment
OntoDL		define concept mouse {		opening the definition scope for the concept "mouse"
OntoDL		Code Mus Display me.Name Definition ($ a small rodent characteristically having a pointed snout, small rounded ears, a body-length scaly tail and a high breeding rate		using a table for setting property values of the concept "mouse": in the first row the property "Code" is set to the string value "Mus". in the 2nd row the value of the property "Display" is set to the concept's name ("mouse") the 3rd row holds a long text with special characters (comma) as the concept's definition. We do not want the OntoDL interpeter to parse through that text, so we prefic it with "($" (we could have put it into parentheses as well to gain the same effect).
OntoDL		}		the concept's definition scope is closed

---

Defining Objects from Internal References

Objects of type "concept" and "system" may be defined through properties of other objects that resolve to these respective types. The most common scenario is to introduce an external code system to OntoDL through the Systems property of the CTS2LE global object:

define system LOINC = CTS2LE.Systems[OID=(2.16.840.1.113883.6.1)]

The same mechanism can be applied for intorducing a concept from an external system:

define concept (hospital letter) = LOINC.Concepts[Code=(68609-7)]

It is important to notice that objects defined through internal references do not have a definiton scope. This is because they adopt all properties except the name from the assigned object. The assignment is "by reference" whoch means that the defined object is just a reference to the source object and therefore all changes applied to the source object will be visible to the newly defined object, too.

In the example below, both concepts "demo" and "demo2" will have a display value of "demonstration" at the end of the definition scope of concept "demo" (Note: This was just to demonstrate the principle. In fact this code would rise an error because there must not be two concepts within the same code system that have the same code).

define concept demo {
  define concept demo2 = me
  set me.Display = (demonstration)
}  

Qualified Concepts

Concepts from external code systems can be introduced by just providing their code together with a reference to the code system:

define concept (hospital letter) = (68609-7)@LOINC

This compact notation is especially useful when defining a value set of codes from external code systems:

define codesystem documenttypes {
  .URI = (http://sample.com/doctypes)
  define concept (hospital letter) = (68609-7)@LOINC
  define concept (referral note)   = (57133-1)@LOINC
  define concept (hospital consult note) = (34104-0)@LOINC
}

Nesting of definition Statements

definition statements may be nested, e.g. a code system definition usualy contains further definition statements for the concepts within the code system. The table below lists which object definitions may be included within the definition scope of other objects.

left=outside top=inside	codesystem	system	concept	property	predicate
codesystem	not allowed	not allowed	top-level concept within the codesystem	property applicable to the code system and all contained objects	predicate applicable to all concepts within the code system
system	not allowed	not allowed	concept within the system. shall be identified by its code	property applicable to the code system and all contained objects. properties values will not be exported	predicate applicable to all concepts within the code system. concepts within the codesystem are only allowed as targets to concept relationships
concept	not allowed	not allowed	sub-concept	property applicable to the concept and all of its sub-concepts	predicate applicable to the concept and all of its sub-concepts
property	not allowed	not allowed	not allowed	not allowed	not allowed
predicate	not allowed	not allowed	not allowed	not allowed	not allowed