BILLY software

[Igor12]

Hello!
In many articles where CRYSTAL is used, I have come across the following phrase

The energy optimization of the basis sets was undertaken using the Billy software.

which is accompanied by a link to the manual. But there is no information about it in the manual or anywhere else. Can anyone explain what it is? Thank you in advance!

[Mo]

https://vallico.net/mike_towler/faqs/faq1.html

[Igor12]

Thank you!