/usr/sap/trans/actlog - directory

[cosmo_polit]

Hi fans,
can somebody of you explain the "right to exist" of the /usr/sap/trans/actlog diectory in SAP systems?!
I have several R/3 lines here and, for a reason I do not know, I have lines with and without a.m. directory.
Can that be a relict of a 4.6 system and is existing since we upgraded to NW 7.0 and nobody noticed it til now?
and also in that case its not longer necessary for anything? or is this directory still needed?
thx in advance and br
cu cosmo_polit