# Pass Parameter to Sub UDT

**URL:** <https://forum.inductiveautomation.com/t/pass-parameter-to-sub-udt/80915>\
**Category:** Ignition\
**Tags:** ignition81, perspective\
**Created:** [October 24, 2023, 4:29pm UTC](https://forum.inductiveautomation.com/t/pass-parameter-to-sub-udt/80915 "2023-10-24T16:29:35Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![amarks](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/amarks/32/45610_2.png) [@amarks](https://forum.inductiveautomation.com/u/amarks)\
**Post date:** [October 24, 2023, 4:29pm UTC](https://forum.inductiveautomation.com/t/pass-parameter-to-sub-udt/80915/1 "2023-10-24T16:29:35Z")

</div>

I have a UDT (B) with a UDT (A) inside. I'm passing a (string) parameter to the sub-UDT via {parameter} in the parameter setup page within the UDT definition.

The parameter is used for extra information on an alarm's display path, if needed. Parameters are configured like so:

```auto
{Display_Path_b} | UDT_B
{Display_Path_a} | UDT_A

```

Within the definition for UDT\_B, the `Display_Path_a` parameter is filled in with `{Display_Path_b}` so that the parameter can be passed down.

However, when there is no extra information to display in the display path, it's left blank. In that case, the literal string '{Display\_Path\_b}' is used.

Why is an empty string not passed to the sub UDT?

As a workaround, my UDT definition now contains a space for that display path property.