# Data structure expression

**URL:** <https://forum.inductiveautomation.com/t/data-structure-expression/4385>\
**Category:** Ignition\
**Created:** [May 1, 2012, 7:08am UTC](https://forum.inductiveautomation.com/t/data-structure-expression/4385 "2012-05-01T07:08:20Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Joseph\_Mendonca](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@Joseph\_Mendonca](https://forum.inductiveautomation.com/u/Joseph_Mendonca)\
**Post date:** [May 1, 2012, 7:08am UTC](https://forum.inductiveautomation.com/t/data-structure-expression/4385/1 "2012-05-01T07:08:20Z")

</div>

Created a data structure where one of the tags, and integer, incorporates an expression. Created several instances but, what was found is that if you override the expression in the instance the tag will error with;  
RuntimeException: Syntax Error on Token: ‘End of Expression’ (Line 0 , Char 0). Deleting the expression in the data structure does not clear the error in the propagated instances. The tag icon in the data structure still has the expression icon over layed on it.

---

<div class="post-metadata">

**Author:** ![Colby.Clegg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/colby.clegg/32/3282_2.png) [@Colby.Clegg](https://forum.inductiveautomation.com/u/Colby.Clegg)\
**Post date:** [May 1, 2012, 4:28pm UTC](https://forum.inductiveautomation.com/t/data-structure-expression/4385/2 "2012-05-01T16:28:18Z")

</div>

What did you override the expression with? What is the base expression? I just did a quick test and it worked, so I think either the instance expression must be somehow marked as overridden, but with an empty expression.

And I don’t quite understand what you mean when you say that you’re deleting the base expression… wouldn’t this result in the instances having a blank expression (unless they were overridden, of course), which would in turn lead to this error? (Note: the error, end of expression, char 0, is caused by an empty expression value)

Regards,

---

<div class="post-metadata">

**Author:** ![Joseph\_Mendonca](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@Joseph\_Mendonca](https://forum.inductiveautomation.com/u/Joseph_Mendonca)\
**Post date:** [May 2, 2012, 11:14pm UTC](https://forum.inductiveautomation.com/t/data-structure-expression/4385/3 "2012-05-02T23:14:50Z")

</div>

The expression was deleted in the base. It was just a simple expression to experiment with UDT’s. Wouldn’t it propagate that change to the incidences?

---

<div class="post-metadata">

**Author:** ![Colby.Clegg](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/colby.clegg/32/3282_2.png) [@Colby.Clegg](https://forum.inductiveautomation.com/u/Colby.Clegg)\
**Post date:** [May 9, 2012, 11:30pm UTC](https://forum.inductiveautomation.com/t/data-structure-expression/4385/4 "2012-05-09T23:30:43Z")

</div>

Hi, sorry for the delayed response.

I’m not quite sure I follow: you say that you deleted the expression, and the error you’re reporting is what you would get with a blank expression… doesn’t that make sense?

Or do you mean that the base has no expression, but the instances do, and they still error? Or did you expect that deleting the expression would clear the overrides?

Regards,