This book includes syntax diagrams as an option for readers who want a more visual representation of XQuery expression syntax. Each syntax diagram is accompanied by explanatory text and examples. Figure P-1 illustrates the components of a syntax diagram, showing the schema import syntax as an example.
Rules for interpreting the syntax diagrams are:
Parts of the diagram in constant width
font are literal values. In Figure P-1, import schema
and at
should appear literally in your query.
Quotes that appear in syntax diagrams also must appear in your query. Figure P-1 shows that the <
namespace-name
>
must be surrounded by quotes, whereas the <
prefix
>
must not. Either single or double quotes can be used in XQuery, but only double quotes are included in the diagrams for simplicity.
Where you can specify a value, such as a name, a descriptive name for that value appears in constant width italic and is surrounded by angle brackets. Figure P-1 shows that you fill in the <
namespace-name
>
, <
prefix
>
, and <
location
>
with your own values.
Multiple options are indicated by parallel lines in the diagram. Figure P-1 shows that you may choose to specify a namespace prefix or default element namespace
.
Optional parts of the expression are indicated by an arrow that bypasses the main arrow. In Figure P-1, it is not necessary to include the namespace <
prefix
> =
or the default element namespace
keywords.
Repeating parts of an expression are indicated by an arrow that returns to the beginning. Figure P-1 shows that you can specify multiple <
location
>
s (preceded by commas) as part of the at
clause.
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