CUP - Custom fields mapping

Hi,

I'm trying to set up field-mapping for additinal custom fields in the CUP request form. I'm not sure, what is the application means in the field-mapping screen, I dont have any thing to select from the list for application field.

Please help me to understand, how to setup application and what it means.

Also, I didn't find enough information, please suggest me if any docs available for this configuration.

Regards - Laks