That does not seem to be true with the latest build of parted. At least, not in the versions currently packaged for Ubuntu 16, Arch, or when compiling from the git master as of 2018/04/08
The doc I referenced above states: "This document applies roughly to version 3.2
of GNU Parted."
Unfortunately, the documented syntax does not appear to be valid. Considering that the documentation index states the docs were last updated in 2016, I'm assuming the syntax online is outdated. https://www.gnu.org/software/parted/manual/
$ ./parted --version
parted (GNU parted) 3.2.94-7188
$ ./parted --help | grep -i mkpart
mkpart PART-TYPE [FS-TYPE] START END make a partition
Indeed, trying to specify a name for `mkpart` results in an error.
Please let me know if there is anything I can to do assist in updating this documentation.