# UserData for mesh face

**URL:** <https://discourse.mcneel.com/t/userdata-for-mesh-face/5278>\
**Category:** Rhino Developer\
**Created:** [January 22, 2014, 2:25pm UTC](https://discourse.mcneel.com/t/userdata-for-mesh-face/5278 "2014-01-22T14:25:27Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![karol\_wierzbicki](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/karol_wierzbicki/32/164716_2.png) [@karol\_wierzbicki](https://discourse.mcneel.com/u/karol_wierzbicki)\
**Post date:** [January 22, 2014, 2:25pm UTC](https://discourse.mcneel.com/t/userdata-for-mesh-face/5278/1 "2014-01-22T14:25:27Z")

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Hi,

Anybody have idea how to apply my data to specific mesh faces? I can do it for whole mesh with use of SetUserString or mesh.UserData, but how to do it for specific faces? Or maybe how to get face guid?

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**Author:** ![karol\_wierzbicki](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/karol_wierzbicki/32/164716_2.png) [@karol\_wierzbicki](https://discourse.mcneel.com/u/karol_wierzbicki)\
**Post date:** [January 22, 2014, 2:36pm UTC](https://discourse.mcneel.com/t/userdata-for-mesh-face/5278/2 "2014-01-22T14:36:16Z")

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OK, I think I have this one. I need to get RuntimeSerialNumber.

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**Author:** ![dale](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/dale/32/685184_2.png) [@dale](https://discourse.mcneel.com/u/dale)\
**Post date:** [January 22, 2014, 6:27pm UTC](https://discourse.mcneel.com/t/userdata-for-mesh-face/5278/3 "2014-01-22T18:27:51Z")

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You cannot store user data on a mesh face, or ON\_MeshFace, as user data can only be stored on class objects that are derived from ON\_Object. But, you can store user data on the mesh itself, or ON\_Mesh.

Does this help?

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<div class="post-metadata">

**Author:** ![karol\_wierzbicki](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/karol_wierzbicki/32/164716_2.png) [@karol\_wierzbicki](https://discourse.mcneel.com/u/karol_wierzbicki)\
**Post date:** [January 23, 2014, 1:24pm UTC](https://discourse.mcneel.com/t/userdata-for-mesh-face/5278/4 "2014-01-23T13:24:27Z")

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I was afraid there is no easy way. Is there an way to get unique data for single face? Maybe uuid?

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<div class="post-metadata">

**Author:** ![dale](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/dale/32/685184_2.png) [@dale](https://discourse.mcneel.com/u/dale)\
**Post date:** [January 23, 2014, 5:13pm UTC](https://discourse.mcneel.com/t/userdata-for-mesh-face/5278/5 "2014-01-23T17:13:57Z")

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Sorry, no. An ON\_MeshFace is a pretty lightweight class, just holding on to its vertex indices.