The target attribute syntax has several parts:
• The first part is the ID of an element in the instance document or a dot segment ( “.” ) indicating that this is a relative address.
• One or more subidentifiers follow. Each is preceded by a literal slash (/) as a path separator. The subidentifiers are taken from a child of the element identified by the first part. For nested elements, multiple subidentifiers can be used to identify the path to the targeted element.
• The final part is optional. If this part is absent, all member values of the target element are targeted (for example, all values of a matrix). If this part is present, it can take one of two forms:
o The name of the member value (field) indicating symbolic access. This notation consists of:
• A literal period (.)indicating member selection access.
• The symbolic name of the member value (field). The “Common Glossary”
subsection later in this chapter documents values for this field under the common
o The cardinal position of the member value (field) indicating array access. This notation consists of:
• A literal left parenthesis ( ( ) indicating array selection access.
• A number of the field, starting at zero for the first field.
• A literal right parenthesis ( ) ) closing the expression.
The array-access syntax can be used to express fields only in one-dimensional vectors and twodimensional matrices.