The interactive stack mode is entered by pressing UP while on the stack. A cursor on the left of the stack indicates the stack is in interactive mode. Pressing ON will exit interactive mode.

While in the interactive stack, you can operate on a single item by simply moving the cursor to that item or on multiple items by selecting them first, then operating on them.

To select multiple items, move the cursor to the item in question, then press SP. The item will be highlighted on the screen. Moving the cursor to other items will extend the selection, and pressing SP again will fix the selection, so the cursor is free to move. The selection is also cleared by another tap of SP.

The most common stack operations are performed using LF and RT. When there's no selection, LF will move the item at the cursor to level 1, while RT will move the item on level 1 to the position pointed by the cursor. Other items in between will move accordingly, effectively causing ROLL and ROLLD with the items between level 1 and the cursor.

When there's a selection, and only if the cursor is within the selected range, LF and RT will do the same but only within the selected range, effectively rotating the selected items.

When there's a selection but the cursor is pointing outside the selected range, LF will move the selected items to the cursor position, while RT will make a copy of the selected items at the cursor position, preserving the original selected range.

The standard clipboard shortcuts will also work on selected items or the item at the cursor location:

• LS^hold-LF will copy the selected objects to the stack;
• LS^hold-RT will paste the clipboard at the current cursor location;
• LS^hold-DN will cut the selected objects, removing them from the stack and leaving a copy on the clipboard.

Pressing EN will create a copy of the object at the cursor position at level 1 (similar to PICK). It works on individual items only.

Pressing BK will drop the item at the cursor position, or the selected items if a selection exists.

The interactive stack makes it simple to create composite objects:

• Pressing MUL will create a vector with the items in the selection or at the cursor position. If the items include vectors or individual items of compatible dimensions, it will create a matrix. It is flexible with the arrangement of individual items and vectors: as long as there is one vector that determines the number of columns in the matrix, individual items can be used to fill the matrix in row order;
• Pressing SUB when there are exactly 2 items selected will create a complex number;
• Pressing ADD will create a list with the items in the selection or at the cursor position.
• Pressing DIV will explode a composite object into its components.