# 7.9 Expression tags and Scan classes

**URL:** <https://forum.inductiveautomation.com/t/7-9-expression-tags-and-scan-classes/59483>\
**Category:** Ignition\
**Tags:** ignition79\
**Created:** [May 12, 2022, 1:54am UTC](https://forum.inductiveautomation.com/t/7-9-expression-tags-and-scan-classes/59483 "2022-05-12T01:54:30Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\
**Post date:** [May 12, 2022, 1:54am UTC](https://forum.inductiveautomation.com/t/7-9-expression-tags-and-scan-classes/59483/1 "2022-05-12T01:54:30Z")

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I’ve gone back in time to v7.9.9 and can’t remember the recommended way to use expression tags. I know these are supposed to use a different scan class, but is that all? I was just going to use leased.

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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:** [May 12, 2022, 2:35am UTC](https://forum.inductiveautomation.com/t/7-9-expression-tags-and-scan-classes/59483/2 "2022-05-12T02:35:06Z")

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You might be thinking of DB/Query tags. I don’t think there’s anything you need to watch out for with Expression tags unless they are abusing the `runScript` function.

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**Author:** ![nminchin](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/nminchin/32/6911_2.png) [@nminchin](https://forum.inductiveautomation.com/u/nminchin)\
**Post date:** [May 12, 2022, 2:37am UTC](https://forum.inductiveautomation.com/t/7-9-expression-tags-and-scan-classes/59483/3 "2022-05-12T02:37:03Z")

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Ok cool 🙂 cheers  
No runScript abuse is happening