The APPSETTING element tag lets you display the value of a setting associated with the active web application.
These settings are entirely dependent on the application itself - every application has its own unique list. If you want to use this tag, you probably already know the name of the setting whose value you want to display, but contact a system administrator to request a list if you aren't sure.
This tag has the following default syntax, where the Property parameter is mandatory:
<%# APPSETTING(Property) %>
An example of a complete APPSETTING tag is as follows:
<%# APPSETTING(CoreAPIURL) %>
When this tag is rendered, it will display the value assigned to the CoreAPIURL setting.