# DDL\_DIC

Version: 3.11.09 (2015-05-07)

## <a name="ALIAS"></a>ALIAS

The attributes used to specify the aliased names of definitions.

### <a name="_alias.definition_id"></a>\_alias.definition\_id

Identifier tag of an aliased definition.

### <a name="_alias.deprecation_date"></a>\_alias.deprecation\_date

Date that the aliased tag was deprecated as a definition tag.

### <a name="_alias.dictionary_uri"></a>\_alias.dictionary\_uri

Dictionary URI in which the aliased definition belongs.

## <a name="CATEGORY"></a>CATEGORY

The attributes used to specify the properties of a
&quot;category&quot; of data items.

### <a name="_category.key_id"></a>\_category.key\_id

Tag of a single data item in a Loop category which is the generic key
to access other items in the category. The value of this
item must be unique in order to provide unambiguous access to
a packet (row) in the table of values.  This may be assumed to be a function
of the datanames listed in category\_key.name.

## <a name="CATEGORY_KEY"></a>CATEGORY\_KEY

The attributes used to specify (possibly multiple) 
keys for a given category.

### <a name="_category_key.name"></a>\_category\_key.name

A minimal list of tag(s) that together constitute a compound key
to access other items in a Loop category. In other words, the combined values of the
datanames listed in this loop must be unique, so that unambiguous access 
to a packet (row) in the table of values is possible.  The dataname associated with
category.key\_id is only included in this loop if no other set of datanames can form
a compound key.

## <a name="DEFINITION"></a>DEFINITION

The attributes for classifying dictionary definitions.

### <a name="_definition.class"></a>\_definition.class

The nature and the function of a definition or definitions.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Attribute</td><td>Item used as an attribute in the definition
 of other data items in DDLm dictionaries. 
 These items never appear in data instance files.</td></tr>
  <tr><td>Functions</td><td>Category of items that are transient function
 definitions used only in dREL methods scripts.
 These items never appear in data instance files.</td></tr>
  <tr><td>Datum</td><td>Item defined in a domain-specific dictionary.  
 These items appear only in data instance files.</td></tr>
  <tr><td>Head</td><td>Category of items that is the parent of
 all other categories in the dictionary.</td></tr>
  <tr><td>Loop</td><td>Category of items that in a data file must
 reside in a loop-list with a key item defined.</td></tr>
  <tr><td>Set</td><td>Category of items that form a set (but not a
 loopable list). These items may be referenced 
 as a class of items in a dREL methods expression.</td></tr>
  <tr><td>Ref-loop</td><td>A category containing one item that identifies the     
 a category of items that is repeated in a sequence
 of save frames. The item, which is specifies as a
 as a Ref-table value (see type.container), is looped. 
 This construction is for loop categories that contain 
 child categories.
 If in the instance file, the child items have only
 one set of values, the Ref-loop item need not be used
 and child items need not be placed in a save frame.</td></tr>
</table>
Default value: 'Datum'

### <a name="_definition.id"></a>\_definition.id

Identifier name of the Item or Category definition contained 
within a save frame.

### <a name="_definition.scope"></a>\_definition.scope

The extent to which a definition affects other definitions.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Dictionary</td><td>applies to all defined items in the dictionary</td></tr>
  <tr><td>Category</td><td>applies to all defined items in the category</td></tr>
  <tr><td>Item</td><td>applies to a single item definition</td></tr>
</table>
Default value: 'Item'

### <a name="_definition.update"></a>\_definition.update

The date that a definition was last changed.

### <a name="_definition.xref_code"></a>\_definition.xref\_code

Code identifying the equivalent definition in the dictionary
referenced by the [DICTIONARY\_XREF](#DICTIONARY_XREF) attributes.

## <a name="DESCRIPTION"></a>DESCRIPTION

The attributes of descriptive (non-machine parseable) parts of
definitions.

### <a name="_description.common"></a>\_description.common

Commonly-used identifying name for the item.

### <a name="_description.key_words"></a>\_description.key\_words

List of key-words categorising the item.

### <a name="_description.text"></a>\_description.text

The text description of the defined item.

## <a name="DESCRIPTION_EXAMPLE"></a>DESCRIPTION\_EXAMPLE

The attributes of descriptive (non-machine parseable) examples of
values of the defined items.

### <a name="_description_example.case"></a>\_description\_example.case

An example case of the defined item.

### <a name="_description_example.detail"></a>\_description\_example.detail

A description of an example case for the defined item.

## <a name="DICTIONARY"></a>DICTIONARY

Attributes for identifying and registering the dictionary. The items
in this category are NOT used as attributes of INDIVIDUAL data items.

### <a name="_dictionary.class"></a>\_dictionary.class

The nature, or field of interest, of data items defined in the dictionary.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Reference</td><td>DDLm reference attribute definitions</td></tr>
  <tr><td>Instance</td><td>domain-specific data instance definitions</td></tr>
  <tr><td>Template</td><td>domain-specific attribute/enumeration templates</td></tr>
  <tr><td>Function</td><td>domain-specific method function scripts</td></tr>
</table>
Default value: 'Instance'

### <a name="_dictionary.date"></a>\_dictionary.date

The date that the last dictionary revision took place.

### <a name="_dictionary.ddl_conformance"></a>\_dictionary.ddl\_conformance

The version number of the DDL dictionary that this dictionary
conforms to.

### <a name="_dictionary.namespace"></a>\_dictionary.namespace

The namespace code that may be prefixed (with a trailing colon
&quot;:&quot;) to an item tag defined in the defining dictionary when used 
in particular applications. Because tags must be unique, namespace
codes are unlikely to be used in data files.

### <a name="_dictionary.title"></a>\_dictionary.title

The common title of the dictionary. Will usually match the name
attached to the data\_ statement of the dictionary file.

### <a name="_dictionary.uri"></a>\_dictionary.uri

The universal resource indicator of this dictionary.

### <a name="_dictionary.version"></a>\_dictionary.version

A unique version identifier for the dictionary.

## <a name="DICTIONARY_AUDIT"></a>DICTIONARY\_AUDIT

Attributes for identifying and registering the dictionary. The items
in this category are NOT used as attributes of individual data items.

### <a name="_dictionary_audit.date"></a>\_dictionary\_audit.date

The date of each dictionary revision.

### <a name="_dictionary_audit.revision"></a>\_dictionary\_audit.revision

A description of the revision applied for the [\_dictionary\_audit.version](#_dictionary_audit.version).

### <a name="_dictionary_audit.version"></a>\_dictionary\_audit.version

A unique version identifier for each revision of the dictionary.

## <a name="DICTIONARY_VALID"></a>DICTIONARY\_VALID

Data items which are used to specify the contents of definitions in
the dictionary in terms of the [\_definition.scope](#_definition.scope)     and the required
and prohibited attributes.

### <a name="_dictionary_valid.application"></a>\_dictionary\_valid.application

Provides the information identifying the definition scope (
from the [\_definition.scope](#_definition.scope) enumeration list) and the validity 
options (from the [\_dictionary\_valid.option](#_dictionary_valid.option) enumeration list), 
as a two element list. This list signals the validity of applying
the attributes given in [\_dictionary\_valid.attributes](#_dictionary_valid.attributes).

### <a name="_dictionary_valid.attributes"></a>\_dictionary\_valid.attributes

A list of the attribute names and categories that are assessed
for application in the item, category and dictionary definitions.

### <a name="_dictionary_valid.scope"></a>\_dictionary\_valid.scope

The scope to which the specified restriction on usable
attributes applies.  

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Dictionary</td><td>restriction applies to dictionary definition data frame</td></tr>
  <tr><td>Category</td><td>restriction applies to a category definition save frame</td></tr>
  <tr><td>Item</td><td>restriction applies to an item definition save frame</td></tr>
</table>
### <a name="_dictionary_valid.option"></a>\_dictionary\_valid.option

Option codes for applicability of attributes in definitions.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Mandatory</td><td>attribute must be present in definition frame</td></tr>
  <tr><td>Recommended</td><td>attribute is usually in definition frame</td></tr>
  <tr><td>Prohibited</td><td>attribute must not be used in definition frame</td></tr>
</table>
Default value: 'Recommended'

## <a name="DICTIONARY_XREF"></a>DICTIONARY\_XREF

Data items which are used to cross reference other dictionaries that
have defined the same data items. Data items in this category are NOT 
    o used as attributes of individual data items.

### <a name="_dictionary_xref.code"></a>\_dictionary\_xref.code

A code identifying the cross-referenced dictionary.

### <a name="_dictionary_xref.date"></a>\_dictionary\_xref.date

Date of the cross-referenced dictionary.

### <a name="_dictionary_xref.format"></a>\_dictionary\_xref.format

Format of the cross referenced dictionary.

### <a name="_dictionary_xref.name"></a>\_dictionary\_xref.name

The name and description of the cross-referenced dictionary.

### <a name="_dictionary_xref.uri"></a>\_dictionary\_xref.uri

The source URI of the cross referenced dictionary data.

## <a name="ENUMERATION"></a>ENUMERATION

The attributes for restricting the values of defined data items.

### <a name="_enumeration.def_index_id"></a>\_enumeration.def\_index\_id

Specifies the data name with a value used as an index to the 
DEFAULT enumeration list (in category enumeration\_default)
in order to select the default enumeration value for the 
defined item. The value of the identified data item must match 
one of the [\_enumeration\_default.index](#_enumeration_default.index) values.

### <a name="_enumeration.default"></a>\_enumeration.default

The default value for the defined item if it is not specified explicitly.

### <a name="_enumeration.mandatory"></a>\_enumeration.mandatory

Yes or No flag on whether the enumerate states specified for an
item in the current definition (in which item appears) MUST be
used on instantiation.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Yes</td><td>Use of state is mandatory</td></tr>
  <tr><td>No</td><td>Use of state is unnecessary</td></tr>
</table>
Default value: 'Yes'

### <a name="_enumeration.range"></a>\_enumeration.range

The inclusive range of values &quot;from:to&quot; allowed for the defined item.

## <a name="ENUMERATION_DEFAULT"></a>ENUMERATION\_DEFAULT

Loop of pre-determined default enumeration values indexed to a 
data item by the item [\_enumeration.def\_index\_id](#_enumeration.def_index_id).

### <a name="_enumeration_default.index"></a>\_enumeration\_default.index

Index key in the list default values referenced to by the value
of [\_enumeration.def\_index\_id](#_enumeration.def_index_id) .

### <a name="_enumeration_default.value"></a>\_enumeration\_default.value

Default enumeration value in the list referenced by the value of
[\_enumeration.def\_index\_id](#_enumeration.def_index_id). The reference index key is given by
the value of [\_enumeration\_default.index](#_enumeration_default.index) value.

## <a name="ENUMERATION_SET"></a>ENUMERATION\_SET

Attributes of data items which are used to define a
set of unique pre-determined values.

### <a name="_enumeration_set.detail"></a>\_enumeration\_set.detail

The meaning of the code (identified by [\_enumeration\_set.state](#_enumeration_set.state))
in terms of the value of the quantity it describes.

### <a name="_enumeration_set.state"></a>\_enumeration\_set.state

Permitted value state for the defined item.

### <a name="_enumeration_set.xref_code"></a>\_enumeration\_set.xref\_code

Identity of the equivalent item in the dictionary
referenced by the [DICTIONARY\_XREF](#DICTIONARY_XREF) attributes.

### <a name="_enumeration_set.xref_dictionary"></a>\_enumeration\_set.xref\_dictionary

Code identifying the dictionary in the [DICTIONARY\_XREF](#DICTIONARY_XREF) 
list.

## <a name="IMPORT"></a>IMPORT

Used to import the values of specific attributes from other dictionary 
definitions within and without the current dictionary.

### <a name="_import.get"></a>\_import.get

A list of tables of attributes defined individually in the category [IMPORT\_DETAILS](#IMPORT_DETAILS),  
used to import definitions from other dictionaries. 

## <a name="IMPORT_DETAILS"></a>IMPORT\_DETAILS

Items in [IMPORT\_DETAILS](#IMPORT_DETAILS) describe individual attributes of an import operation.

### <a name="_import_details.file_id"></a>\_import\_details.file\_id

The file name/URI of the source dictionary

### <a name="_import_details.frame_id"></a>\_import\_details.frame\_id

The framecode of the definition frame to be imported.

### <a name="_import_details.order"></a>\_import\_details.order

	The order in which the import described by the referenced row should be      	
   executed.

### <a name="_import_details.if_dupl"></a>\_import\_details.if\_dupl

Code identifying the action taken if the requested definition block 
already exists within the importing dictionary.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Ignore</td><td>ignore imported definitions if id conflict</td></tr>
  <tr><td>Replace</td><td>replace existing with imported definitions</td></tr>
  <tr><td>Exit</td><td>issue error exception and exit</td></tr>
</table>
Default value: 'Exit'

### <a name="_import_details.if_miss"></a>\_import\_details.if\_miss

Code identifying the action taken if the requested definition block 
is missing from the source dictionary.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Ignore</td><td>ignore import</td></tr>
  <tr><td>Exit</td><td>issue error exception and exit</td></tr>
</table>
Default value: 'Exit'

### <a name="_import_details.mode"></a>\_import\_details.mode

Code identifying how a definition save frame is to be imported.
&quot;Full&quot; imports the entire definition frame including the leading 
       and trailing save statements.
&quot;Contents&quot; imports only the lines within the save frame.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Full</td><td>import requested definition with frame</td></tr>
  <tr><td>Contents</td><td>import contents of requested defn frame</td></tr>
</table>
Default value: 'Contents'

### <a name="_import_details.single"></a>\_import\_details.single

A Table mapping attributes defined individually in category IMPORT to
their values; used to import definitions from other dictionaries.  

### <a name="_import_details.single_index"></a>\_import\_details.single\_index

One of the indices permitted in the entries of values of attribute [\_import\_details.single](#_import_details.single).

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>file</td><td>filename/URI of source dictionary</td></tr>
  <tr><td>save</td><td>save framecode of source definition</td></tr>
  <tr><td>mode</td><td>mode for including save frames</td></tr>
  <tr><td>dupl</td><td>option for duplicate entries</td></tr>
  <tr><td>miss</td><td>option for missing duplicate entries</td></tr>
</table>
## <a name="LOOP"></a>LOOP

Attributes for looped lists.

### <a name="_loop.level"></a>\_loop.level

Specifies the level of the loop structure in which a defined
item must reside if it used in a looped list.

Default value: '1'

## <a name="METHOD"></a>METHOD

Methods used for evaluating, validating and defining items.

### <a name="_method.expression"></a>\_method.expression

The method expression for the defined item.

### <a name="_method.purpose"></a>\_method.purpose

The purpose and scope of the method expression.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Evaluation</td><td>method evaluates an item from related item values</td></tr>
  <tr><td>Definition</td><td>method generates attribute value(s) in the definition</td></tr>
  <tr><td>Validation</td><td>method compares an evaluation with existing item value</td></tr>
</table>
Default value: 'Evaluation'

## <a name="NAME"></a>NAME

Attributes for identifying items and item categories.

### <a name="_name.category_id"></a>\_name.category\_id

The name of the category in which a category or item resides.

### <a name="_name.linked_item_id"></a>\_name.linked\_item\_id

Dataname of an equivalent item in another category which has a 
common set of values, or, in the definition of a type Su
item is the name of the associated Measurement item to 
which the standard uncertainty applies.

### <a name="_name.object_id"></a>\_name.object\_id

The object name of a category or name unique within the 
category or family of categories.

## <a name="TYPE"></a>TYPE

Attributes which specify the &#39;typing&#39; of data items.

### <a name="_type.container"></a>\_type.container

The CONTAINER type of the defined data item value. 

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Single</td><td>single value</td></tr>
  <tr><td>Multiple</td><td>values as List or by boolean ,|&amp;!* or range : ops</td></tr>
  <tr><td>List</td><td>ordered set of values bounded by [] and separated by
                             commas. Elements need not be of same contents type.</td></tr>
  <tr><td>Array</td><td>ordered set of numerical values bounded by [] and 
                             separated by commas. Operations across arrays are
                             equivalent to operations across elements of the Array.</td></tr>
  <tr><td>Matrix</td><td>ordered set of numerical values for a tensor bounded by 
                             [] and separated by commas. Tensor operations such as
                             dot and cross products, are valid cross matrix objects.</td></tr>
  <tr><td>Table</td><td>id:value elements bounded by {}; separated by commas</td></tr>
  <tr><td>Ref-table</td><td>a STAR construction with key:value elements bounded
                             by ${..}$ and separated by commas.
                             The id tags below are privileged and optional.
                             source  - filename or URI
                             block   - data blockname
                             frame   - framecode or [framecode,framecode,..]
                             item    - dataname or [dataname,dataname,..]
                             key     - key value if item is in a list</td></tr>
</table>
Default value: 'Single'

### <a name="_type.contents"></a>\_type.contents

Syntax of the value elements within the container type. 
This may be a single enumerated code, or, in the case of a list, 
a comma-delimited sequence of codes, or, if there are alternate 
types, a boolean-linked (or range) sequence of codes.
The typing of elements is determined by the replication 
of the minimum set of states declared.   Where the definition is of
a &#39;Table&#39; container this attribute describes
the construction of the value elements within those (Table) values.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Text</td><td>case-sens strings or lines of STAR characters</td></tr>
  <tr><td>Code</td><td>case-insens contig. string of STAR characters</td></tr>
  <tr><td>Name</td><td>case-insens contig. string of alpha-num chars or underscore</td></tr>
  <tr><td>Tag</td><td>case-insens contig. STAR string with leading underscore</td></tr>
  <tr><td>Filename</td><td>case-sens string indentifying an external file</td></tr>
  <tr><td>Uri</td><td>case-sens string as universal resource indicator of a file</td></tr>
  <tr><td>Date</td><td>ISO standard date format &lt;yyyy&gt;-&lt;mm&gt;-&lt;dd&gt;</td></tr>
  <tr><td>Version</td><td>version digit string of the form &lt;major&gt;.&lt;version&gt;.&lt;update&gt;</td></tr>
  <tr><td>Dimension</td><td>integer limits of an Array/Matrix/List in square brackets</td></tr>
  <tr><td>Range</td><td>inclusive range of numerical values min:max</td></tr>
  <tr><td>Count</td><td>unsigned integer number</td></tr>
  <tr><td>Index</td><td>unsigned non-zero integer number</td></tr>
  <tr><td>Integer</td><td>positive or negative integer number</td></tr>
  <tr><td>Real</td><td>floating-point real number</td></tr>
  <tr><td>Imag</td><td>floating-point imaginary number</td></tr>
  <tr><td>Complex</td><td>complex number &lt;R&gt;+j&lt;I&gt;</td></tr>
  <tr><td>Binary</td><td>binary number \b&lt;N&gt;</td></tr>
  <tr><td>Hexadecimal</td><td>hexadecimal number \x&lt;N&gt;</td></tr>
  <tr><td>Octal</td><td>octal number \o&lt;N&gt;</td></tr>
  <tr><td>Implied</td><td>implied by the context of the attribute</td></tr>
  <tr><td>ByReference</td><td>The contents have the same form as those of the attribute referenced by
                            _type.contents_referenced_id.</td></tr>
</table>
Default value: 'Text'

Examples:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>
Integer
  </td><td>content is a single or multiple integer(s)
  </td></tr>
  <tr><td>
Real,Integer
  </td><td>List elements of a real number and an integer
  </td></tr>
  <tr><td>
List(Real,Code)
  </td><td>List of Lists of a real number and a code
  </td></tr>
  <tr><td>
Text|Real
  </td><td>content is either text OR a real number
  </td></tr>
</table>
### <a name="_type.contents_referenced_id"></a>\_type.contents\_referenced\_id

The value of the [\_definition.id](#_definition.id) attribute of an attribute definition
whose type is to be used also as the type of this item.  Meaningful only
when this item&#39;s [\_type.contents](#_type.contents) attribute has value &#39;ByReference&#39;.

### <a name="_type.dimension"></a>\_type.dimension

The dimensions of a list or matrix of elements as a text string 
within bounding square brackets.

Examples:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>
[3,3]
  </td><td>3x3 matrix of elements
  </td></tr>
  <tr><td>
[6]
  </td><td>list of 6 elements
  </td></tr>
  <tr><td>
[]
  </td><td>unknown number of list elements
  </td></tr>
</table>
### <a name="_type.indices"></a>\_type.indices

Used to specify the syntax construction of indices of the entries in the
defined object when the defined object has &#39;Table&#39; as its
[\_type.container](#_type.container) attribute.  Values are a subset of the codes and
constructions defined for attribute [\_type.contents](#_type.contents), accounting
for the fact that syntactically, indices are always case-sensitive
quoted strings.

Meaningful only when the defined item has [\_type.container](#_type.container) &#39;Table&#39;.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Text</td><td>a case-sensitive string/lines of text</td></tr>
  <tr><td>Filename</td><td>name of an external file</td></tr>
  <tr><td>Code</td><td>code used for indexing data or referencing data resources</td></tr>
  <tr><td>Date</td><td>ISO date format yyyy-mm-dd</td></tr>
  <tr><td>Uri</td><td>an universal resource identifier string, per RFC 3986</td></tr>
  <tr><td>Version</td><td>version digit string of the form &lt;major&gt;.&lt;version&gt;.&lt;update&gt;</td></tr>
  <tr><td>ByReference</td><td>Indices have the same form as the contents of the attribute identified by
_type.indices_referenced_id</td></tr>
</table>
Default value: 'Text'

Examples:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>
Code
  </td><td>indices belong to an enumerated set of pre-defined codes
  </td></tr>
  <tr><td>
Uri
  </td><td>indices have the form of URIs
  </td></tr>
</table>
### <a name="_type.indices_referenced_id"></a>\_type.indices\_referenced\_id

The [\_definition.id](#_definition.id) attribute of a definition whose type describes the
form and construction of the indices of entries in values of the present item.

Meaningful only when the defined item&#39;s [\_type.container](#_type.container) attribute has
value &#39;Table&#39;, and its [\_type.indices](#_type.indices) attribute has value &#39;ByReference&#39;.

### <a name="_type.purpose"></a>\_type.purpose

The primary purpose or function the defined data item serves in a
dictionary or a specific data instance.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Import</td><td>&gt;&gt;&gt; Applied ONLY in the DDLm Reference Dictionary &lt;&lt;&lt;
 Used to type the SPECIAL attribute &quot;_import.get&quot; that
 is present in dictionaries to instigate the importation
 of external dictionary definitions.</td></tr>
  <tr><td>Method</td><td>&gt;&gt;&gt; Applied ONLY in the DDLm Reference Dictionary &lt;&lt;&lt;
 Used to type the attribute &quot;_method.expression&quot; that 
 is present in dictionary definitions to provide the 
 text method expressing the defined item in terms of
 other defined items.</td></tr>
  <tr><td>Audit</td><td>&gt;&gt;&gt; Applied ONLY in the DDLm Reference Dictionary &lt;&lt;&lt;
 Used to type attributes employed to record the audit 
 definition information (creation date, update version and
 cross reference codes) of items, categories and files.</td></tr>
  <tr><td>Identify</td><td>&gt;&gt;&gt; Applied ONLY in the DDLm Reference Dictionary &lt;&lt;&lt;
 Used to type attributes that identify an item tag (or
 part thereof), save frame or the URI of an external file. </td></tr>
  <tr><td>Extend</td><td>*** Used to EXTEND the DDLm Reference Dictionary ***
 Used in a definition, residing in the &quot;extensions&quot; 
 save frame of a domain dictionary, to specify a new
 enumeration state using an Evaluation method.</td></tr>
  <tr><td>Describe</td><td>Used to type items with values that are descriptive
 text intended for human interpretation.</td></tr>
  <tr><td>Encode</td><td>Used to type items with values that are text or codes 
 that are formatted to be machine parsible.</td></tr>
  <tr><td>State</td><td>Used to type items with values that are restricted to 
 codes present in their &quot;enumeration_set.state&quot; lists.</td></tr>
  <tr><td>Key</td><td>Used to type an item with a value that is unique within   
 the looped list of these items, and may be used as a
 reference &quot;key&quot; to identify a specific packet of items 
 within the category.</td></tr>
  <tr><td>Link</td><td>Used to type an item with a value that is unique within
 a looped list of items belonging to another category.
 The definition of this item must contain the attribute
 &quot;_name.linked_item_id&quot; specifying the data name of the
 key item for this list. The defined item represents a
 a foreign key linking packets in this category list to 
 packets in another category.</td></tr>
  <tr><td>Composite</td><td>Used to type items with value strings composed of
 separate parts. These will usually need to be separated 
 and parsed for complete interpretation and application.</td></tr>
  <tr><td>Number</td><td>Used to type items that are numerical and exact (i.e. 
 no standard uncertainty value). </td></tr>
  <tr><td>Measurand</td><td>Used to type an item with a numerically estimated value 
 that has been recorded by measurement or derivation. This 
 value must be accompanied by its standard uncertainty 
 (SU) value, expressed either as:
   1) appended integers, in parentheses (), at the
      precision of the trailing digits,       or
   2) a separately defined item with the same name as the 
      measurand item but with an additional suffix &#39;_su&#39;.</td></tr>
  <tr><td>SU</td><td>Used to type an item with a numerical value that is the 
 standard uncertainty of an item with the identical name
 except for the suffix &#39;_su&#39;. The definition of an SU item 
 must include the attribute &quot;_name.linked_item_id&quot; which
 explicitly identifies the associated measurand item.</td></tr>
  <tr><td>Internal</td><td>Used to type items that serve only internal purposes of the dictionary
 in which they appear.  The particular purpose served is not defined by
 this state.</td></tr>
</table>
Default value: 'Describe'

### <a name="_type.source"></a>\_type.source

The origin or source of the defined data item, indicating by what 
recording process it has been added to the domain instance.

Values:

<table>
  <tr><th>Value</th><th>Description</th></tr>
  <tr><td>Recorded</td><td>A value (numerical or otherwise) recorded by
 observation or measurement during the experimental 
 collection of data. This item is PRIMITIVE.</td></tr>
  <tr><td>Assigned</td><td>A value (numerical or otherwise) assigned as part of
 the data collection, analysis or modelling required
 for a specific domain instance. These assignments 
 often represent a decision made that determines the
 course of the experiment (and therefore may be deemed
 PRIMITIVE) or a particular choice in the way the data
 was analysed (and therefore may be considered NOT
 PRIMITIVE). </td></tr>
  <tr><td>Related</td><td>A value or tag used in the construction of looped   
 lists of data. Typically identifying an item whose
 unique value is the reference key for a loop category
 and/or an item which as values in common with those 
 of another loop category and is considered a Link
 between these lists.</td></tr>
  <tr><td>Derived</td><td>A quantity derived from other data items within the 
 domain instance. This item is NOT PRIMITIVE.</td></tr>
</table>
Default value: 'Selected'

## <a name="UNITS"></a>UNITS

The attributes for specifying units of measure.

### <a name="_units.code"></a>\_units.code

A code which identifies the units of measurement.

Default value: 'Arbitrary'

