# Confused about permissions and tags

**URL:** <https://forum.inductiveautomation.com/t/confused-about-permissions-and-tags/52468>\
**Category:** Ignition\
**Tags:** ignition80, perspective\
**Created:** [October 28, 2021, 4:40pm UTC](https://forum.inductiveautomation.com/t/confused-about-permissions-and-tags/52468 "2021-10-28T16:40:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![codersmurf](https://avatars.discourse-cdn.com/v4/letter/c/df788c/32.png) [@codersmurf](https://forum.inductiveautomation.com/u/codersmurf)\
**Post date:** [October 28, 2021, 4:40pm UTC](https://forum.inductiveautomation.com/t/confused-about-permissions-and-tags/52468/1 "2021-10-28T16:40:58Z")

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So if I have a udt and in it i have 6 tags, 5 coils and one integer. The integer tag is an expression tag that takes the coils and writes a number in itself. The coils are coming from a plc. Does the expression tag need to be readOnly=false for it to write to itself?Thx

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**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\
**Post date:** [October 28, 2021, 4:42pm UTC](https://forum.inductiveautomation.com/t/confused-about-permissions-and-tags/52468/2 "2021-10-28T16:42:53Z")

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No, that shouldn’t be necessary.

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**Author:** ![codersmurf](https://avatars.discourse-cdn.com/v4/letter/c/df788c/32.png) [@codersmurf](https://forum.inductiveautomation.com/u/codersmurf)\
**Post date:** [October 28, 2021, 4:44pm UTC](https://forum.inductiveautomation.com/t/confused-about-permissions-and-tags/52468/3 "2021-10-28T16:44:05Z")

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Cool, thx