Certain reading systems or distribution platforms impose limits on the size of individual files within an EPUB. The lowest known limit stems from legacy Adobe readers, which could not handle files exceeding 300 KB; content beyond this threshold would fail to display.

Objectives

• Ensure EPUB files are compatible with legacy reading systems that have technical constraints.
• Maximize interoperability across different reading tools and platforms.
• Improve the performance and loading speed of EPUB files.

Implementation

• Split XHTML files into segments smaller than 300 KB.

Control

• Check the file size of all XHTML documents.