In your previous mail you wrote:

   By the way, BSD uses lots of singly-linked lists, probably because it
   comes from a time when there was not so much memory.
   
=> no, BSDs use an include ([/usr/include]/sys/queue.h) which provides
C macros for singly-linked lists, singly-linked tail queues, lists
and tail queues. So programmers just select the best data structure for
each job (and as BSD programmers are skilled programmers they use
signly-linked lists as soon as they don't need a list feature).
Note this is not very bound to memory: in many cases there are
some structures with better memory use, for instance lists in arrays
from Python (standard C implementation).

Thanks

Francis.Dupont@fdupont.fr

PS: just type "man queue" on a BSD (including MacOS X). If it is
not enough try "man tree" (but not yet on my MacOS X, sorry)...