I'm trying to make sure I don't do something catastrophic by
misunderstanding.

I do

lvcreate --name ascii-root --size 3G jessie

to create a logical volume called "ascii-root" within the volume
group "jessie".

Then I look at the result by

ls /dev/mapper

and get:

root@notlookedfor:/# lvcreate --name ascii-root --size 3G jessie
  Logical volume "ascii-root" created
root@notlookedfor:/# ls /dev/mapper
control            jessie-devuan--home  jessie-devuan--usr  jessie-tmp
jessie-ascii--root  jessie-devuan--root  jessie-devuan--var
root@notlookedfor:/# 

Now I get it that it concatenates the folume group name, a hyphen,
and the logical volume name.

But why does it stick an extra hyphen in the logical volume name?

jessie-ascii--root

-- hendrik