How to use `<sub>`/`<sup>` in record shape?

How to use <sub>/<sup> in record shape?
Or, how to ensure a smallest height and weight for html node?
I am drawing a b+-tree with like Pn-1.
In record with “” I cannot use <sub>/<sup>.
In html empty node is too small. And it is hard to make shapes in the same height.

The docs say <sub> and <sup> are supported. Do they not work? Could you post your input file?

digraph g1 {

node [shape=record];
root[label="<f0> P<sub>n-1</sub>|<f1>"];

dot -Tsvg -o test.svg
Error: bad label format <f0> P<sub>n-1</sub>

<sub> and <sup> are only supported for HTML-like labels, not for record-based nodes.

Here is how to write your example to use HTML-like labels:
[dot verbose=true]

digraph g1 {
    node [shape=plaintext]
    root [label=<
                    <TD port="f0">P<SUB>n-1</SUB></TD>
                    <TD port="f1"></TD>


NOTE: This renders incorrectly using Firefox, but correctly with Chrome.

In case you are not using Chrome, here is a png image generated offline:


See also: