Archival storage
The item was preserved in a compact analog format rather than left only as paper.
What does microfiche mean
In everyday use, the word microfiche refers both to the physical sheet itself and to the information stored on it. If a catalog says a newspaper, dissertation, or record is on microfiche, it means you will access it through a magnifying reader rather than as a standard paper copy or a normal digital file.
Break the word into two ideas:
Together, microfiche means a small-scale information sheet: a flat film sheet holding reduced document images.
The item was preserved in a compact analog format rather than left only as paper.
You normally cannot read the contents without magnification because each page image is heavily reduced.
The collection may predate digital scanning, so microfiche is often the version researchers still consult.