how can the F4 help for fund variable displayed as key and not text?

Hello,

I have created a varaible (interval varaible) for Fund, but the selection option is displayed as text (the description) of the Fund, the user wants it to be key (Fund number) rather than text.

Where can I do this setting, i did not see this setting while creating the varaible.

Please give some inputs.

Thanks in advance