# About items not in the document

**URL:** <https://community.blockcerts.org/t/about-items-not-in-the-document/2308>\
**Category:** Technical\
**Created:** [February 3, 2020, 2:34am UTC](https://community.blockcerts.org/t/about-items-not-in-the-document/2308 "2020-02-03T02:34:55Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![taira](https://avatars.discourse-cdn.com/v4/letter/t/67e7ee/32.png) [@taira](https://community.blockcerts.org/u/taira)\
**Post date:** [February 3, 2020, 2:34am UTC](https://community.blockcerts.org/t/about-items-not-in-the-document/2308/1 "2020-02-03T02:34:55Z")

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Hey!!  
In the document ([https://github.com/blockchain-certificates/cert-schema/blob/master/docs/schema-2.md](https://github.com/blockchain-certificates/cert-schema/blob/master/docs/schema-2.md)), “SignatureLine”, “RecipientProfile”, “MerkleProof2017” etc. are “undefined” and details are unknown is. Is there any documentation about this?  
Also, Learning-machine’s sample JSON has “nonce” and “universalIdentifier” items, which are also missing from the documentation. Is it your own extension item? .

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**Author:** ![aronning](https://avatars.discourse-cdn.com/v4/letter/a/47e85d/32.png) [@aronning](https://community.blockcerts.org/u/aronning)\
**Post date:** [February 4, 2020, 1:21pm UTC](https://community.blockcerts.org/t/about-items-not-in-the-document/2308/2 "2020-02-04T13:21:33Z")

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That schema was created with a json to markdown tool which isn’t always perfect in detecting certain details - displays `undefined` sometimes. You can find the documentation inside of the json files themselves [https://github.com/blockchain-certificates/cert-schema/tree/master/cert\_schema/2.0](https://github.com/blockchain-certificates/cert-schema/tree/master/cert_schema/2.0)

And yes, you can view the contexts of some of the learning machine sample json files and see that additional fields are sometimes added.