debian package version epoch
The version string of a Debian package, as displayed by the
dpkg -l command, follows this format:
[epoch:]upstream_version[-debian_revision]. Only the
upstream_version part is required, and the other parts are optional.
See the description of the debian-package-version inspector for more information.
debian package version epoch returns the
epoch part of the string or an empty string, if that part is absent. The epoch is an unsigned integer, typically a small number. The epoch allows the package provider to create a fresh start with version numbering schemes.
The name structure of Debian package versions is documented here.