At the bottom of certain articles in the Research Wiki you might find something like this
CID123456 Please do not erase or change this identification number.
This number is the collection idendtification number. It is important as it is used by FamilySearch Record Search to link from certain collection to their corresponding articles in the wiki. Each collection identification number is unique and it is important that the format not be changed as it may effect the ability of FamilySEarch Record Search to link to articles. It has been a longstanding goal of FamilySearch to integrate its various resouces and to provide as many access points as possible.