In Debian’s version string syntax the version consists of three parts:
[epoch:]upstream_version[-debian_revision]
The ‘epoch’ and ‘debian_revision’ parts are optional.
Example of such version strings:
60.7.2esr-1~deb9u1 52.9.0esr-1~deb9u1 1:2.3.4-1+b2 327-2 1:1.0.13-3 2:1.19.2-1+deb9u5
If the ‘debian_revision part’ is not present, hyphens ‘-’ are not allowed. If epoch is not present, colons ‘:’ are not allowed.
If these parts are present, hyphen and/or colons can appear only once in valid Debian version strings.
In GNU Coreutils, such restrictions are not reasonable (a file name can have many hyphens, a line of text can have many colons).
As a result, in GNU Coreutils hyphens and colons are treated exactly like all other punctuation, i.e., they are sorted after letters. See Version sort punctuation.
In Debian, these characters are treated differently than in Coreutils: a version string with hyphen will sort before similar strings without hyphens.
Compare:
$ touch 1ab-cd 1abb $ ls -v -1 1abb 1ab-cd $ if dpkg --compare-versions 1abb lt 1ab-cd > then echo sorted > else echo out of order > fi out of order
For further details, see Comparing two strings using Debian’s algorithm and GNU Bug 35939.