# User defined Parameters

**URL:** <https://forum.certara.com/t/user-defined-parameters/4349>\
**Category:** General\
**Tags:** phoenix-86\
**Created:** [November 28, 2025, 4:00pm UTC](https://forum.certara.com/t/user-defined-parameters/4349 "2025-11-28T16:00:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Kamel\_Moktefi](https://avatars.discourse-cdn.com/v4/letter/k/f17d59/32.png) [@Kamel\_Moktefi](https://forum.certara.com/u/Kamel_Moktefi)\
**Post date:** [November 28, 2025, 4:00pm UTC](https://forum.certara.com/t/user-defined-parameters/4349/1 "2025-11-28T16:00:46Z")

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Hi,

I tried to add AUC0\_6\_%extrap as (AUC0-6-AUClast)/(AUC0-6)\*100. But AUC0-6 was considered a variable not valid even though AUC0-6 was selected as is from the list in the Definition field.

 ![image](https://us1.discourse-cdn.com/certara/original/2X/d/dde1d75dbc7a490f06d15eb53fc6bbbdf5d23daa.png)

Thanks.

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**Author:** ![SimonDavis](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@SimonDavis](https://forum.certara.com/u/SimonDavis)\
**Post date:** [November 28, 2025, 5:54pm UTC](https://forum.certara.com/t/user-defined-parameters/4349/2 "2025-11-28T17:54:43Z")

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Please try naming it AUC0\_6 or some other name that does not include - which it probably does not like because it secondary calculations it think it is a minus.  
If you still have an issue, please email a project exhibiting the issue to Support@certara.  
Simon

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**Author:** ![Kamel\_Moktefi](https://avatars.discourse-cdn.com/v4/letter/k/f17d59/32.png) [@Kamel\_Moktefi](https://forum.certara.com/u/Kamel_Moktefi)\
**Post date:** [November 28, 2025, 7:11pm UTC](https://forum.certara.com/t/user-defined-parameters/4349/3 "2025-11-28T19:11:13Z")

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Thank you for the quick replay.

I can confirm with you that it is not a problem of naming the AUC0-6. I tried all strategies. The issue is in Phoenix because it uses a nomenclature of AUC0-6 where the sign “-“ is considered as a mathematical operation. Phoenix should list AUC0\_6 in the Definition list.

Best regards,

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**Author:** ![SimonDavis](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@SimonDavis](https://forum.certara.com/u/SimonDavis)\
**Post date:** [January 7, 2026, 1:23pm UTC](https://forum.certara.com/t/user-defined-parameters/4349/4 "2026-01-07T13:23:21Z")

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Kamel, coming back to this because I still don’t understand how you got 0-6 inthe couln name unless you specifically asked for it; the default syntax is underscores;

 ![image](https://us1.discourse-cdn.com/certara/original/2X/8/835874428e7a284c758cf46aae950a4c55670fd8.png)

but you could have overuled it here ?

 ![image](https://us1.discourse-cdn.com/certara/original/2X/b/bfbf945a6a5a93e0e46a4b7bc020405dbc40c3ce.png)

Happy New Year, Simon.