- XML (Extensible Markup Language) Reader/Writer
- XML Quick Facts
- Workbench XML Reader Parameters
- Workbench XML Writer Parameters
- Feature Representation
- Mapping File Reference
- xfMap
- Reading the Input XML Document
- Mapping Rules
- Types of Mapping Rules
- Match and Except Expression
- Specifying Several Match Expressions for One Mapping Rule
- Limiting Mapping Rule Activation with Except Expressions
- Mapping Rule States (activation, execution, suspension, and de-activation)
- Using Force Elements During Mapping Rule Activation and Deactivation
- Search-sets
- Expression Elements (Extract and Literal)
- Expression Sequence
- Feature Mapping Rules
- FME Feature Construction
- Feature Type Element
- Attributes Element
- FME Feature Construction (defining mapping rules under the <feature-content-map> element)
- Attribute Element (handling multiple values)
- Attribute Element (handling optional attributes)
- Attribute Element (sequenced attributes)
- Attribute Element (Nillable Attributes)
- Geometry Element
- Geometry Builder States (activation, execution, suspension, and de-activation)
- Geometry Construction
- Composite Geometry Builders
- Built-in Geometry Builders
- xml-point
- xml-point-xy
- xml-line
- xml-area
- xml-donut
- xml-aggregate
- xml-box
- xml-text
- xml-path
- xml-arc
- xml-arc-by-center-point
- xml-elliptical-arc
- xml-circle
- xml-polygon
- xml-face
- xml-composite-surface
- xml-triangulated-surface
- xml-enclosed-surface
- xml-composite-solid
- xml-multi-point
- xml-multi-curve
- xml-multi-area
- xml-multi-text
- xml-multi-surface
- xml-multi-solid
- xml-null
- xml-reverse-geometry
- fme-geometry
- Mapping Segmented Geometric Information
- Geometry Traits (trait element)
- FME Feature Construction (constructing multiple features at a time)
- Structure Element
- References Element
- Apply References Element
- Group Mapping Rules
- Reference Mapping Rules
- Mapping Rules (Optional Elements)
- More Expression Elements
- FME Schema Features
- Reading the Input XML Document
You are here: Popular Formats > XML (Extensible Markup Language) Reader/Writer > xfMap > Expression Elements (Extract and Literal)
Many of the elements that make up a mapping rule need some kind of information as input. The xfMap provides a general input mechanism with expression elements. We can therefore start to discuss these expression elements regardless of the xfMap elements that may use them.
Expression elements are so called because they contain an expr attribute whose value we call the expression string. This section describes two types of expression elements: the extract and literal expressions. Other types of expression elements are described in later sections.