This section describes some of the operations you can perform on a Stack, they modify the existing frames in some way
Reverse Order does just that, it makes the old Top Frame the new Frame 0, and viserversa. Unused Frames are not modified.
Resize and Align Functions This is a big subject and will be covered elsewhere.
Filter Stack is an immediate filter operation, whatever filter you have set up will be applied to each frame in turn, and the original frame overwritten. It can be useful for filtering noisy frames before stacking, you could Save Work, Filter All Frames, Do Stack, and finally Reload All Frames to get a better picture in some cases.
The Make Monochrome function on the Frame menu gives you the option of applying it to the whole stack.
Balance Colour and Brightness of which there are three varieties tries to make a Frame look like one of it's neighbours, the Global version finds the average colour and brightness of the reference frame then adjusts the other frame to match. The other two functions find these values but for the immediate vecinity of the point being adjusted. All three functions do not alter the Active Frame but gradually move up and down the stack away from it balancing frames as they go. Thus it is advisable to choose the 'best looking' frame before invoking one of these functions.
Replace Groups, Average this will reduce the number of frames in a stack by averageing together groups of frames, each group is the same size, except possibly the last one. If there are too many frames for stacking, or the difference between frames is too gradual use this function. Another less obvious use is to reduce noise, take several pictures at each camera setting and then average each group together to produce a noise free Frame.
Horizontal Skew This function moves the frames in the stack progressively from left to right. Once skewed in this way don't use Do Stack but use one of the average functions without Automatic alignment. You can display some of the 3d characteristics of a stack in a 'Rocking' movie by repeated use of this function. It is best used in a Macro to generate Rocking movies.
It is possible to build Macros to modify the stack in other ways e.g. I created one that expands the stack by inserting an additional frame between each pair which is intermediate between them.