Content Rendering Customization
In some cases you want a content item to act and/or look different then its default behavior. Different way to render your content can be registered (like different templates), and each way are associated to a “customization marker”. On your content, in SMI, you can after select one of those “customization marker”, and the associated templates to that marker will be used to render your content.
In other words, a “customization marker” allows you to customize the look and feel for a specific content item.
Customization markers can be defined both on the file–system (in a extension), and in ZODB. They can be used as well in the service_customization to customize, in ZODB, a template.
Customization button
To customize a content item you need to click the customization... button available in the properties screen. (Fig. 1.)

Fig. 1. Clicking the customization button.
Adding a customization marker
After clicking this button you get a screen that makes it possible to mark content with a “customization marker” form the Available markers. To add one you select the marker(s) and click the Add button. (Fig. 2.)

Fig. 2. Selecting and adding the PhotoGallery marker.
The selected marker will modify the rendering of your content, in this case it will render the content as a photo gallery.
Removing a customization marker
Removing a marker is just as easy as adding one. Select the marker(s) you want to remove from the Used markers list and click the Remove button. (Fig. 3.)

Fig. 3. Removing the PhotoGallery marker.