Github Formatted Markdown Identifiers
```
% pandoc -f man+gfm_auto_identifiers -t html
.TH "TEST" "1" "2026-05-08"  "test v1.0.0" "test manual"
.SH 1st HEADING
.SH C++ & Rust
.SH HEADING
.SH HEADING
^D
<h1 id="1st-heading">1st HEADING</h1>
<h1 id="c--rust">C++ &amp; Rust</h1>
<h1 id="heading">HEADING</h1>
<h1 id="heading-1">HEADING</h1>
```

Ascii Identifiers test
```
% pandoc -f man+ascii_identifiers -t html
.TH "TEST" "1" "2026-05-08"  "test v1.0.0" "test manual"
.SH Über den Flüssen
^D
<h1 id="uber-den-flussen">Über den Flüssen</h1>
```

Headers without Auto Identifiers test
```
% pandoc -f man-auto_identifiers -t native
.TH "TEST" "1" "2026-05-08"  "test v1.0.0" "test manual"
.SS Level 2
.SS different styles:
.SS Ordered
.SS Ordered
^D
[ Header
    2 ( "" , [] , [] ) [ Str "Level" , Space , Str "2" ]
, Header
    2
    ( "" , [] , [] )
    [ Str "different" , Space , Str "styles:" ]
, Header 2 ( "" , [] , [] ) [ Str "Ordered" ]
, Header 2 ( "" , [] , [] ) [ Str "Ordered" ]
]
```