Terminology and Notation

Throughout the rest of this documentation, we will rely on some simple terminology and notation:

  • In esc’s interface, the stack window shows numbers from top to bottom. To avoid wasting large amounts of space in the documentation, we often describe the stack in terms of a Python list, with the leftmost element showing at the top, so a stack containing the numbers 1, 2, 3, and 4 from top to bottom would be described as [1, 2, 3, 4].

  • Certain elements on the stack need to be discussed frequently and have shorthand names in the documentation, interface, and code:

    • bos (Bottom of Stack) – the item listed at the bottom of the Stack window, 4 in the example above
    • sos (Second on Stack) – the item listed second from the bottom of the Stack window, 3 in the example above
    • tos (Top of Stack) – the item listed at the top of the Stack window, 1 in the example above