The details of PyTorch Linux binaries *.wkl

What is the difference between cu90/torch-0.3.1-cp27-cp27mu-linux_x86_64.whl and
cu90/torch-0.3.1-cp27-cp27m-linux_x86_64.whl. In details, what does ‘u’ in ‘cp27mu’ mean? And cp27 means ‘Python 2.7.x’?

As far as I know, the cp27m(u) defines the ABI-tag (application binary interface).
While cp27m defines the usage of narrow-unicode, cp27mu uses wide-unicode.

The cp27 is the python tag and defines the python version.

You can find more information on this in PEP513 or the pypa/manylinux repo.