#### 16.9.1 Understanding DITA2Go expandable drop-down sections

An expandable drop-down section allows a user to click a link to optionally display additional material; then click the link again (or click the displayed material) to collapse the section and hide the material.

For DITA2Go output, the link can be based on any of the following:

- a special block-element @outputclass dedicated to drop-down links
- an existing block element in your document, such as a figure title or table title
- a graphic icon, with or without accompanying text
- a button, instead of text
- a fixed text string.

A drop-down section has four main parts: link start, link end, block start, and block end. Each new drop-down link gets a new value for predefined macro variable <$$_DropID>, which is used in all following blocks until the next link, or until the end of the HTML file. This means that a single link can optionally control multiple blocks; the blocks do not have to be contiguous.

Each link/block set is independent of other sets. Opening one block does not close other blocks that might have been opened from other links.

DITA2Go provides built-in macros to use for drop-down sections, and settings to enable and deploy the macros. To use the built-in DITA2Go macros as is for drop-down sections, you do not have to include their definitions in your configuration file. Include a drop-down macro definition only to edit or replace the macro.

In its simplest form, a DITA2Go drop-down section needs only one [HTMLParaStyles] format property assigned in the configuration file, and rarely more than two; but has enough configurable options to do almost anything you might want.

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Parent Topic: 16.9 Including expandable sections in Help topics

Sibling Topics:

16.9.2 Setting up expandable sections for your document

16.9.3 Delimiting expandable drop-down sections

16.9.4 Configuring drop-down links

16.9.5 Configuring drop-down blocks

16.9.6 Providing CSS for drop-down links and blocks

16.9.7 Deploying JavaScript code for drop-down sections

16.9.8 Emulating Web Works Publisher drop-down hotspots