# HTML Mask This is a [composite generator](/app/generation/generators/generator-types/generators-composite.md). 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](/app/generation/generators/generator-reference/passthrough.md) * [Constant](/app/generation/generators/generator-reference/constant.md) * [Null](/app/generation/generators/generator-reference/null.md) --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.tonic.ai/app/generation/generators/generator-reference/html-mask.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.