# HTML Mask This is a [composite generator](https://docs.tonic.ai/app/generation/generators/generator-types/generators-composite). Masks text columns by parsing the contents as HTML, and applying sub-generators to specified path expressions. If applying a sub-generator fails because of an error, the generator selected as the fallback generator is applied instead. Path expressions are defined using the [XPath syntax](https://www.w3schools.com/xml/xpath_syntax.asp). For example, for the following HTML: ```html

Title

Paragraph content

Item 1
Item 2
Item 3

``` To get the value of `h1`, the expression is `//h1/text(`). To get the value of the first list item, the expression is `//ul/li[1]/text()`. ## Characteristics


Consistency	Determined by the selected sub-generators.
Linking	Determined by the selected sub-generators.
Differential privacy	Determined by the selected sub-generators.
Data-free	Determined by the selected sub-generators.
Allowed for primary keys	No
Allowed for unique columns	No
Uses format-preserving encryption (FPE)	No
Privacy ranking	5
Generator ID (for the API)	`HtmlMaskGenerator`

## How to configure ### Adding a sub-generator To assign a generator to a path expression: 1. Under **Sub-generators**, click **Add Generator**.\ \ On the sub-generator configuration panel, the **Cell HTML** field contains a sample value from the source database. You can use the previous and next icons to page through different values. 2. In the **Path Expression** field, type the path expression to identify the value to apply the generator to.\ \ **Matched HTML Values** shows the result from the value in **Cell HTML**. 3. From the **Generator Configuration** dropdown list, select the generator to apply to the path expression.\ \ You cannot select another composite generator. 4. Configure the selected generator.\ \ You cannot configure the selected generator to be consistent with another column. 5. To save the configuration and immediately add a generator for another path expression, click **Save and Add Another**.\ \ To save the configuration and close the add generator panel, click **Save**. ### Managing the sub-generators list From the **Sub-Generators** list: * To edit a generator assignment, click the edit icon. * To remove a generator assignment, click the delete icon. * To move a generator assignment up or down in the list, click the up or down arrow. ### Selecting the fallback generator From the **Fallback Generator** dropdown list, select the generator to use if the assigned generator for a path expression fails. The options are: * [Passthrough](https://docs.tonic.ai/app/generation/generators/generator-reference/passthrough) * [Constant](https://docs.tonic.ai/app/generation/generators/generator-reference/constant) * [Null](https://docs.tonic.ai/app/generation/generators/generator-reference/null)