Thoughtstreams seems to recognize footnote syntax, but the resulting markup seems to be partially-escaped HTML.

Example:

    This is body text[^1].
    
    [^1]: This is a footnote

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This is body text[^1].

[^1]: This is a footnote

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I suspect we need to whitelist <sup> and <hr> in the sanitization step. I'll look into it.

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`<sup>`, `<sub>`, `<hr>` and some related attributes are now whitelisted.