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Chapter 6. Prologs

6.1. Setters.
6.1.1. Default collation
6.1.2. Default ordering mode
6.1.3. Default ordering behaviour for empty sequences
6.1.4. Default decimal format
6.2. Global variables
6.3. Functions
This section introduces prologs, which allows declaring functions and global variables that can then be used in the main query. A prolog also allows setting some default behaviour.
MainModule
Figure 6.1. MainModule

Prolog
Figure 6.2. Prolog

The prolog appears before the main query and is optional. It can contain setters and module imports, followed by function and variable declarations.
Module imports are explained in the next chapter.

6.1. Setters.

Setter
Figure 6.3. Setter

Setters allow to specify a default behaviour for various aspects of the language.

6.1.1. Default collation

DefaultCollationDecl
Figure 6.4. DefaultCollationDecl

This specifies the default collation used for grouping and ordering clauses in FLWOR expressions. It can be overriden with a collation directive in these clauses.

6.1.2. Default ordering mode

OrderingModeDecl
Figure 6.5. OrderingModeDecl

This specifies the default behaviour of from clauses, i.e., if they bind tuples in the order in which items occur in the binding sequence. It can be overriden with ordered and unordered expressions.

6.1.3. Default ordering behaviour for empty sequences

EmptyOrderDecl
Figure 6.6. EmptyOrderDecl

This specifies whether empty sequences come first or last in an ordering clause. It can be overriden by the corresponding directives in such clauses.

6.1.4. Default decimal format

DecimalFormatDecl
Figure 6.7. DecimalFormatDecl

DFPropertyName
Figure 6.8. DFPropertyName

This specifies a default decimal format for the builtin function format-number().