What is a program called that contains many missing pieces to be filled in?

A program that contains many missing pieces to be filled in is referred to as skeleton code. Skeleton code provides a basic framework or structure for the program but lacks the full implementation of its functionalities. It serves as a type of blueprint, guiding developers on how to complete the code by filling in the essential parts.

This approach is commonly used in software development to help programmers focus on the core logic of their application while having a clear outline of where their contributions are needed. Skeleton code can streamline the development process, making it easier to understand how different components will work together once fully implemented.

While stub code can also refer to incomplete code, it typically consists of simpler placeholder functions that have been defined but not fully implemented. Patch code refers to small pieces of software designed to fix bugs or improve performance, and helper code generally provides utility functions that assist in common tasks. Thus, skeleton code is the term that best captures the notion of a program's outline waiting for further development.