In reply to Wingnut:
plain tube with sleeve for inserting of karrimat sections
Compression straps run in sleeves at side of sack and emerge at back. This helps prevent snagging.
Two ice-axe loops at back.
Lid has small external pocket with small clip for keys inside. Rope strap on underside of lid.
Crampon attachment points on top of lid.
Simple waist belt
That's it
Bob