Dc.required_category.ee_addon is a project mainly written in PHP, based on the View license.
Makes categories required for selected weblogs. Moreover, categories can be set to have a exact count not to be greater than a certain maximum.
Download Required Category Extension.
Unpack the archive contents to your Desktop or to a location of your choice on your hard-drive.
Copy the extensions/ext.dc_required_category.php file to your
/system/extensions directory of your EE installation
Copy the language/english/lang.dc_required_category.php file to
your /system/language/english directory (or duplicate and modify
for any other language).
This extension does not have any special activation requirements. Follow these steps to activate Required Category in your EE installation:
Log in to your EE control panel
Go to System Administration > Utilities > Extensions Manager and
enable extensions if not enabled already
Enable Required Category extension
The settings for this extension reside in the weblog preferences for each weblog
Weblog Administration › Weblog Management › Edit Weblog