Xad is part of MorphOS it is used in various places.

XAD2LhA 12637 ----rwed 07-Sep-13 10:39:06
XADLibInfo 3067 ----rwed 07-Sep-13 10:39:06
XADList 7039 ----rwed 07-Sep-13 10:39:06
XADUnDisk 13044 ----rwed 07-Sep-13 10:39:06
XADUnFile 9682 ----rwed 07-Sep-13 10:39:06
XADUnTar 10056 ----rwed 07-Sep-13 10:39:06

There is no need to install anything.

Geit