Lift your brow frequently, in puzzlement or apprehension or thought, and "horizontal forehead creases," the very common "worry lines," will appear and lay like a musical staff across your forehead.

Now they have something else in common: this week both announced a further round of mass lay-offs.

The purpose of this article is to lay out the basic issues, common strategies and patterns, and some recommendations as to when and how to use locking strategies.