# Versioning / Serialization of Blocks - Where does it live?

**URL:** https://forum.makecode.com/t/versioning-serialization-of-blocks-where-does-it-live/8259
**Category:** PXT
**Created:** [May 21, 2021, 11:28pm UTC](https://forum.makecode.com/t/versioning-serialization-of-blocks-where-does-it-live/8259 "2021-05-21T23:28:46Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![BeksOmega](https://avatars.discourse-cdn.com/v4/letter/b/bbce88/32.png) [@BeksOmega](https://forum.makecode.com/u/BeksOmega)
#### Post date: [May 21, 2021, 11:28pm UTC](https://forum.makecode.com/t/versioning-serialization-of-blocks-where-does-it-live/8259/1 "2021-05-21T23:28:46Z")

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Hello!

I’m doing some research into how different forks of Blockly handle custom serialization and versioning of blocks. I’ve already checked out the [xml.js](https://github.com/microsoft/pxt-blockly/blob/develop/core/xml.js) file in pxt-blockly, but I was wondering if there was anywhere else I should check?

Thank you for your time =)  
–Beka

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### Author: ![hena3250](https://avatars.discourse-cdn.com/v4/letter/h/cab0a1/32.png) [@hena3250](https://forum.makecode.com/u/hena3250)
#### Post date: [May 26, 2021, 8:37am UTC](https://forum.makecode.com/t/versioning-serialization-of-blocks-where-does-it-live/8259/2 "2021-05-26T08:37:31Z")

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Suppose, for example, that in a serialized hash map, an object was stored under two different You’ll learn about versioning issues shortly.