# What are the constraints for 'id' member?

**URL:** <https://discuss.jsonapi.org/t/what-are-the-constraints-for-id-member/380>\
**Category:** Uncategorized\
**Created:** [March 7, 2016, 12:20pm UTC](https://discuss.jsonapi.org/t/what-are-the-constraints-for-id-member/380 "2016-03-07T12:20:13Z")\
**Posts on this page:** 1\
**Showing post:** 6

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**Author:** ![fdrake](https://sea2.discourse-cdn.com/flex016/user_avatar/discuss.jsonapi.org/fdrake/32/654_2.png) [@fdrake](https://discuss.jsonapi.org/u/fdrake)\
**Post date:** [December 18, 2019, 6:15pm UTC](https://discuss.jsonapi.org/t/what-are-the-constraints-for-id-member/380/6 "2019-12-18T18:15:08Z")

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There doesn’t appear to be anything in the spec that requires “id” values be mapped into URLs, though the examples happen to do so. Is there a need to specify any constraints on the IDs?

For something like the top-level API entry point discussed in [How to handle multiple endpoints/links](https://discuss.jsonapi.org/t/how-to-handle-multiple-endpoints-links/212/3), it even seems reasonable to use an empty string as the ID.

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