!!! Overview 
[{$pagename}] in the [Nds.conf] file specifies the number of hours unused [NDS External References] are allowed to exist before being removed. 

The default value is 192 hours (8 Days) and the range is 1-384 hours. 

The value may also be set in [Imonitor].

!! More Information 
There might be more information for this subject on one of the following: 
[{ReferringPagesPlugin before='*' after='\n' }]