What is the Custom Deployment Location option used for?
Oracle Service Cloud versions November 2010 to current
The Custom Deployment Location (CDL) is a directory or location where the deployment files are stored in your local network.
This location will be either on individual workstations or a shared network location. This location will be used to store and deploy client files and libraries (the files that are usually downloaded from the Oracle server to the workstation by each staff member upon initial log in). When this option is enabled, these files are downloaded once from the Oracle servers and stored at the location you define, conserving bandwidth. In addition, because they are stored outside the staff member’s profile, the files can be accessed by multiple users, reducing the amount of disk space required for deploying the Service Cloud application.
For more information on this, refer to your version's Support Documentation. Within the specific version support documentation, access the "Client Deployment Guide" and search for 'Define a Custom Deployment Location"