# Revocation of a removed comment won't work

**URL:** https://discuss.prosemirror.net/t/revocation-of-a-removed-comment-wont-work/939
**Category:** Uncategorized
**Created:** [August 26, 2017, 7:24am UTC](https://discuss.prosemirror.net/t/revocation-of-a-removed-comment-wont-work/939 "2017-08-26T07:24:50Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![yeanzhi](https://discuss.prosemirror.net/user_avatar/discuss.prosemirror.net/yeanzhi/32/399_2.png) [@yeanzhi](https://discuss.prosemirror.net/u/yeanzhi)
#### Post date: [August 26, 2017, 7:24am UTC](https://discuss.prosemirror.net/t/revocation-of-a-removed-comment-wont-work/939/1 "2017-08-26T07:24:50Z")

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visit [http://prosemirror.net/examples/collab/#edit-Example](http://prosemirror.net/examples/collab/#edit-Example)

1. add a comment
2. delete it
3. undo

Removed comment will not appear。

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<div class="post-metadata">

### Author: ![marijn](https://discuss.prosemirror.net/user_avatar/discuss.prosemirror.net/marijn/32/15_2.png) [@marijn](https://discuss.prosemirror.net/u/marijn)
#### Post date: [August 26, 2017, 9:03pm UTC](https://discuss.prosemirror.net/t/revocation-of-a-removed-comment-wont-work/939/2 "2017-08-26T21:03:20Z")

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This is expected – the undo history tracks the _document_, and comments are metadata that isn’t part of the document. How to properly address this is an open problem.