org-mode table: how to add the left-most vertical line with column groups notation?

Question

The documentation suggests that column groups syntax is a general way to add vertical lines in a table.

For instance, the following org-mode's table snippet

|--------+----------|
|        | Column 1 |
|--------+----------|
| /      | <>       |
| Line 1 |          |
|--------+----------|

is rendered in pdf as

and in ASCII as

--------+----------+
        | Column 1 |
--------+----------+
 Line 1 |          |
--------+----------+

(Apparently, this doesn't work for HTML as the boundaries are controlled by CSS).

My question is: how to use column groups to obtain the left-most vertical line?

The idea is to use one syntax to export the table with specific vertical lines in different formats.

I'm aware of the alternative way to achieve it using #+ATTR_LaTeX: :align |c|c|, but it's specific to LaTeX.

Answer 1

This answer suggests adding one extra column to achieve what is required, i.e.

|---+--------+----------|
|   |        | Column 1 |
|---+--------+----------|
| / | <      | <>       |
|   | Line 1 |          |
|---+--------+----------|