Attribute Lists – XFM Linkages
XML-based Feature Modeling (XFM) linkages may exist in two forms.
The primary form contains Universally Unique Identifier (UUID) values which are used to associate non-graphical XFM feature store elements with other graphical elements, and with each other in a one-to-one relationship. XFM features may actually be a hierarchy of elements related by these linkages; however, the focus of the DGNV8 Reader is to read XFM linkages for the purpose of providing an association of potential XFM feature properties with a specific graphical element in an XFM feature hierarchy.
This primary form is part of the representation of a normalized form of XFM features. See the Bentley Map XFM Design format for an alternative object representation.
A secondary form of XFM linkage simply stores XFM XML information on an element. If the linkage is one of these types, then these attribute list item names are used to specify the values for the linkage:
|
Linkage Parameter |
Contents |
| xfm_data_prefix |
A binary encoded string value for the bytes prefixing the UUID values in an XFM UUID linkage. This is application-specific, but may be calculated by the Writer if not supplied. This attribute has an alias as igds_xfm_data_prefix. Range: Valid 4-byte binary encoded string Default: No default |
| xfm_parent_uuid |
A UUID for the parent XFM feature for this element in a potential XFM feature hierarchy. If this element is the root XFM feature, then this linkage attribute will be a UUID of all zeros. This attribute has an alias as igds_xfm_parent_uuid. Range: Any UUID value in string format Default: UUID of all zeros |
| xfm_root_uuid |
A UUID for the root XFM feature for this element in a potential XFM feature hierarchy. If this element is the root XFM feature, then this linkage attribute will be the same as the xmf_uuid linkage attribute. This attribute has an alias as igds_xfm_root_uuid. Range: Any UUID value in string format Default: The same value as the xfm_uuid attribute |
| xfm_uuid |
A UUID for this XFM feature element. This linkage attribute has no default, and is required by the Writer to create an XFM UUID linkage. This attribute has an alias as igds_xfm_uuid. Range: Any UUID value in string format Default: No default |
Attribute Lists – string linkage
If the linkage is of type string, then these attribute list item names are used to specify the values for the string linkage:
|
Linkage Parameter |
Contents |
|
stringId |
The key or identifier of the string linkage. This is application-specific, but required on write. Range: Unsigned 32-bit integer Default: No default |
|
string |
The text data of the string linkage, in system encoding. Range: Any string Default: No default |
XFM Feature Stores
XFM Feature Stores correspond to IGDS element type 39.
These features represent the non-graphic portion of instances of Bentley Map XML-base Feature Modeling (XFM) features, as a part of a normalized representation of XFM features. See the Bentley Map XFM Design format for an alternative object representation.
They are elements that contain XML strings representing XFM feature properties. They may also contain a set of XFM UUID linkages which consist of Universally Unique Identifiers (UUIDs). These XFM linkages may occur on both XFM feature store elements and on other graphical elements in order to associate these elements with each other. XFM features may actually be a hierarchy of elements related by XFM linkages, and it is the relationship of an XFM feature store and an associated element represent an node in an instance of an XFM feature with its graphics and properties. The focus of the DGNV8 Reader is to read XFM feature stores for the purpose of providing XFM properties with a specific graphical element in an XFM feature hierarchy.
XFM feature store elements have an igds_type of igds_xfmstore, and the attributes shown below.
As a convenience, if the DGN V8 Writer is given features with an igds_type other than igds_xfmstore which has an igds_xfmstore_xml attribute, an XFM feature store element will be automatically created. Such a feature will also create a graphical element and the XFM linkages required to relate such an element to the new XFM feature store element. Furthermore, the name of XFM feature to create in this case may be specified by the igds_xfm_name attribute.
| Attribute Name | Contents |
|---|---|
| igds_xfmstore_appid_word0 |
The first two bytes of the application identifier for an XFM feature store element. This is not used by the Writer. Valid unsigned 16-bit integer 1 for elements with XFM UUID linkage attributes and 7 for elements without XFM UUID linkage attributes |
| igds_xfmstore_appid_word1 |
The second two bytes of the application identifier for an XFM feature store element. This is not used by the Writer. Valid unsigned 16-bit integer 22564 |
| igds_xfmstore_storeid |
The store identifier string for an XFM feature store element. This is not used by the Writer. Valid store id string XMLf |
| igds_xfmstore_url |
The UNICODE (UTF-16) encoded string for a URL. Potentially points to an XML schema. Any valid URL string No default |
| igds_xfmstore_xml |
The UNICODE (UTF-16) encoded string for an XFM feature store XML fragment. Any valid XML String No default |