The <rule> Element

Definition and Usage

The <rule> element defines simple rules for defining either alternative components or alternative descriptors.

The id attribute is the rule identifier. A rule is established by comparing (comparator attribute) a variable (var attribute) value with an absolute value. The variable shall be a property of the settings node (<media> element of application/x-ncl-settings type), that is, the var attribute must have as its valuea property name of the <media> element of “application/x-ncl-settings” type.

Syntax

Element Attributes Content Parent
<rule> id, var, comparator, value <ruleBase> or <compositeRule>

Attributes

Name Value Description
id It may receive any string value that begins with a letter or an underscore and that only contains letters, digits, “.”, and “_”. The id attribute uniquely identifies the element within a document.
var It may receive any string value that begins with a letter or an underscore and that only contains letters, digits, “.”, and “_”. The var attribute uniquely identifies a property name of the settings node (<media> element of “application/x-ncl-settings” type).
comparator “eq”, “ne”, “gt”, “lt”, “gte”, or “lte”. The comparator attribute compares the value of the property specified by the var attribute with the absolute value specified in the value attribute.
value String. The value attribute defines a value to be compared with the property value referred by the var attribute.
Back to top