\levelstay{What problem does this solve?}
Suppose you write an article about octopuses.
This article might have a sections ``Life cycle'' and ``Habitat''.
Now suppose you want to write an article on sea animals and you want to have a section on octopuses.
Obviously, we would like to import the octopus article we already wrote as a section of the sea animals article, but this is nontrivial because we need to somehow convert the habitat and lifecycle sections into subsections only when importing the octopus sub-document into the sea animal article!
This package provides the \fixedwidth{subimportlevel} macro to make that possible.

For a very detailed discussion on the issue of modularity and how this package solves it, see \href{https://danielsank.github.io/tex_modularity/}{https://danielsank.github.io/tex\_modularity}.