This is a short description of the DTD used to define the XML documents which represent a serialization form of Regular Expression Constraints in the Clark System. Each document is a collection of one or more serialized RE Constraints.

<!DOCTYPE CLaRK_reg_constraints [
<!ELEMENT CLaRK_reg_constraints (comment?,regConstraint+)>

The comment element here is optional and will not be processed by the system.

<!ELEMENT comment (#PCDATA)>
<!ELEMENT regConstraint (name, regExpr, tokenizer?, filter?, defaultXPath?)>

Element regConstraint represents a single Regular Expression Constraint in the system. Here is a description of all its sub-elements:

- name - an unique identifier for the constraint in the system.There is no restriction for its content;
- regExpr - a valid regular expression for ClarkSystem;
- tokenizer - a name of a tokenizer which will be used when precessing text data;
- filter - a name of a filter which will be used when precessing text data;
- defaultXPath - a XPath expression which by default will be in the input field of the window for applying the constraint. This is only for user ease.

<!ELEMENT name (#PCDATA)>
<!ELEMENT regExpr (#PCDATA)>
<!ELEMENT filter (#PCDATA)>
<!ELEMENT tokenizer (#PCDATA)>
<!ELEMENT defaultXPath (#PCDATA)>
]>

An Example with two serialized Regular Expression Constraints:

<CLaRK_reg_constraints>
<regConstraint>
<name>reg constraint name 1</name>
<regExpr>&lt;a&gt;,&lt;b&gt;?,&lt;c&gt;+</regExpr>
<tokenizer>MixedWord</tokenizer>
<defaultXPath>/child::para</defaultXPath>
</regConstraint>
<regConstraint>
<name>reg constraint name 2</name>
<regExpr>$NUMBER+,$SPACE*</regExpr>
<tokenizer>Default</tokenizer>
<defaultXPath>//pages</defaultXPath>
</regConstraint>
</CLaRK_reg_constraints>