A RelativePath is a structure that describes a sequence of References and Nodes to follow. Annex A of OPC 10000-4 describes a text format for a RelativePath that can be used in documentation or in files used to store configuration information.
The components of a RelativePath text format are specified in Table 11.
|
Symbol |
Meaning |
|
/ |
The forward slash character indicates that the Server is to follow any subtype of HierarchicalReferences. |
|
. |
The period (dot) character indicates that the Server is to follow any subtype of a Aggregates ReferenceType. |
|
<[#!ns:]ReferenceType> |
A 0:String delimited by the ‘<’ and ‘>’ symbols specifies the BrowseName of a ReferenceType to follow. By default, any References of the subtypes the ReferenceType are followed as well. A ‘#’ placed in front of the BrowseName indicates that subtypes should not be followed. A ‘!’ in front of the BrowseName is used to indicate that the inverse Reference should be followed. The BrowseName may be qualified with a namespace index (indicated by a numeric prefix followed by a colon). This namespace index is used specify the namespace component of the BrowseName for the ReferenceType. If the namespace prefix is omitted then namespace index 0 is used. |
|
[ns:]BrowseName |
A 0:String that follows a ‘/’, ‘.’ or ‘>’ symbol specifies the BrowseName of a target Node to return or follow. This BrowseName may be prefixed by its namespace index. If the namespace prefix is omitted then namespace index 0 is used. Omitting the final BrowseName from a path is equivalent to a wildcard operation that matches all Nodes which are the target of the Reference specified by the path. |
|
& |
The & sign character is the escape character. It is used to specify reserved characters that appear within a BrowseName. A reserved character is escaped by inserting the ‘&’ in front of it. Examples of BrowseNames with escaped characters are: Received browse path name Resolves to “&/Name_1” “/Name_1” “&.Name_2” “.Name_2” “&:Name_3” “:Name_3” “&&Name_4” “&Name_4” |