regina-normal-doc 5.1-6ubuntu1 (s390x binary) in ubuntu focal

 Regina is a software package for low-dimensional topologists. This package
 provides a rich users' handbook, complete API documentation for the C++
 calculation engine and Python bindings, and the full specification for
 Regina's XML data file format.
 .
 Regina focuses on the study of 3-manifold and 4-manifold triangulations,
 normal surfaces, and angle structures. For Regina's standard graphical
 user interface, and for more information about what Regina can do, see
 the package regina-normal.