It's a mix of the Copland OS login system (as seen on Serial Experiments Lain) and the name of the main character of Haibane Renmei. "OLD HOME," seen here as the computer/domain name, is the lodging where Rakka (and ultimately most of the haibane) reside. Both series were made by Abe Yoshitoshi.

I cannot see how this is a "what."

Azuretan said:
I cannot see how this is a "what."

Because it isn't. It was even explained in the comment circa two years ago.