Intro / XCSL / XCSL Project

Element CS
Description Is the root element of an XML Constraint Specification Document. A XCSL constraint document consists of one or more CONSTRAINT elements.
Required true
Attributes
DTD name of DTD that is to be associated with the constraints being specified; Required: false
DATE XCSL document’s date; Required: false
VERSION XCSL document’s version. Required: false
Childrens CONSTRAINT
Parent /
DTD 
<!ELEMENT CS (CONSTRAINT)+>
<!ATTLIST CS
      DTD CDATA #IMPLIED
      DATE CDATA #IMPLIED
      VERSION CDATA #IMPLIED
>

Element CONSTRAINT
Description This element specifies a constraint and the action that will be triggered when this constraint is not respected. This element is formed by a sequence of elements: a SELECTOR element, zero or more LET elements, a CC element, and an ACTION element.
Required true
Childrens SELECTOR LET CC ACTION
Parent CS
DTD 
<!ELEMENT CONSTRAINT (SELECTOR, LET*, CC, ACTION)>

Element SELECTOR
Description This element, as the name suggests, selects the context (the element or elements) within which the conditions should be tested.
Required true
Attributes
SELEXP this attribute should hold an XPath (XML Path Language) expression that performs the selection. Required: true
Parent CONSTRAINT
DTD 
<!ELEMENT SELECTOR EMPTY>

Element LET
Description That elements have an important role in complex constraints, they allow us to specify multi-step evaluations, enabling the simplification of very complex constraints. With this element we can save, in a variable (NAME) the result of an XPath expression applied to any XPath path, or still the set of values that belong to that context. It is an empty element.
Required false
Attributes
NAME it specifies the variable’s name; Required: true
VALUE XPath expression applied to a context or to any XPath path. Required: true
Parent CONSTRAINT
DTD 
<!ELEMENT LET EMPTY>
<!ATTLIST LET
      NAME CDATA #REQUIRED
      VALUE CDATA #REQUIRED
>

Element CC
Description It is an element that specifies the constraint that has to be verified – regular expression or XPath function. The action will be triggered whenever that expression or function is evaluated to false. It has a mixed content – text in which VARIABLE elements can occur any number of times.
Required true
Childrens VARIABLE
Parent CONSTRAINT
DTD 
<!ELEMENT CC (#PCDATA | VARIABLE)*>

Element VARIABLE
Description This element is used when we are enforcing a constraint over an element or attribute and we want to guarantee that that element or attribute is present in the document instance. If the element or attribute in question is absent from the document, the CONSTRAINT will not be evaluated.
Required true
Attributes
SELEXP it consists in the XPath path to that element or elements. Required: true
Parent CC
DTD 
<!ELEMENT VARIABLE EMPTY>
<!ATTLIST VARIABLE
      SELEXP CDATA #REQUIRED
>

Element ACTION
Description It is a required element that returns messages or results of evaluated expressions when the constraint being evaluated results in a false value. It consists of a sequence of messages. The contents of the MESSAGE element is returned when the ACTION element is unchained. It has mixed content: text with VALUE elements.
Required true
Childrens MESSAGE
Parent CONSTRAINT
DTD 
<!ELEMENT ACTION (MESSAGE*)>

Element MESSAGE
Description The contents of the this element is returned when the ACTION element is unchained. It has mixed content: text with VALUE element.
Required false
Childrens VALUE
Parent ACTION
DTD 
<!ELEMENT MESSAGE (#PCDATA | VALUE)*>

Element VALUE
Description This element is used to include some value of elements or attributes in the messages.
Required false
Attributes
SELEXP consists in a XPath path to the element or attribute which value we want to show. Required: true
Parent MESSAGE
DTD 
<!ELEMENT VALUE EMPTY>
<!ATTLIST VALUE
      SELEXP CDATA #REQUIRED
>