1(a). A thing inside which you write notes. Plus the document model used — a mix of different kinds of "cells" — has a history of being called a "notebook int

1(a). A thing inside which you write notes. Plus the document model used — a mix of different kinds of "cells" — has a history of being called a "notebook interface" (cf. Mathematica, IPython/Jupyter notebook, https://www.quora.com/What-is-a-notebook-interface-in-programming https://www.quora.com/What-is-a-notebook-interface-in-progra...).