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 |
| xml_data_prefix |
A binary encoded string value for the bytes prefixing XML data in a secondary form XFM XML linkage. This is used by the Writer to recreate the same XFM XML linkage read by the Reader, however, this data may be calculated by the writer if not supplied. Range: Valid 32-byte binary encoded string Default: No default |
| xml_data |
A UNICODE (UTF-16) encoded string containing the XML data in a secondary form XFM XML linkage. Range: Any valid XML string Default: No default |