topic Re: <UND></UND> Tags work inconsistently in Arcade in ArcGIS Pro Questions

Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Tue, 03 Feb 2026 16:52:12 GMT

I am trying to underline the first line in a three line label.

ownlab1 = $feature.ParcelID

ownlab1 = '<UND>'+Text(ownlab1)+'</UND>'

The resulting labels sometimes work and sometimes don't.

I get '3232' for example, which is what I want, but also, '<UND>3234</UND>' I can't figure out what is different about lines that honor the underline tag and those which reject it.

Is there any logical reason for this?

Thank you,

Randy McGregor

Re: Tags work inconsistently in Arcade

KenBuja — Tue, 03 Feb 2026 17:34:04 GMT

If the text contains a "<" or "&", these special characters break formatting tags. You have to replace them with "<" and "&". This line replaces both (and uses template literals)

`<UND>${Replace(Replace($feature.ParcelID, "&", "&"), "<", "<")}</UND>`

Re: Tags work inconsistently in Arcade

Robert_LeClair — Tue, 03 Feb 2026 17:48:07 GMT

@RandyMcGregor_BMcD - I tested this with some of my data and noticed a few formatting issues with your label expression. Instead of a two line arcade expression, how about this -

"<UND>"+$feature.ParcelID+"</UND>"

It works in my ArcGIS Pro 3.6.x

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Tue, 03 Feb 2026 18:27:18 GMT

Thanks Ken and Robert, I'll give it a try!

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Wed, 04 Feb 2026 12:42:08 GMT

No effect, but I appreciate the suggestion. What's weird is that it works on most labels but not others. My guess is that there are some weird characters are in the mix (but they are not clearly visible.). Maybe a unicode vs straight text deal or something nightmarish like that 😕 Thank you.

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Wed, 04 Feb 2026 12:43:14 GMT

Thanks Ken,

There are no visible troublemaker characters but there may be something 'wrong' with the values that are ignoring the <UND></UND> tags.

Re: Tags work inconsistently in Arcade

KenBuja — Wed, 04 Feb 2026 14:00:40 GMT

What else is in your multi-line string? Do the other elements have the special characters?

Re: Tags work inconsistently in Arcade

Robert_LeClair — Wed, 04 Feb 2026 15:14:57 GMT

That is odd certainly. Is the ParcelID field a text field or a numeric field? I wonder if you could create a new field say "opposite" of ParcelID and then use the Field Calculator to populate the field? By "opposite" I mean, if it's a numeric field, then create a new text field to do the field calculation upon, then apply the UND arcade to the new field for testing purposes.

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Wed, 04 Feb 2026 18:10:09 GMT

Oookay, so I decided to enter text and it's still being naughty:

var ownlab1 = "<UND>"+"Hi Mom"+"_</UND>"

Re: Tags work inconsistently in Arcade

KenBuja — Wed, 04 Feb 2026 18:43:26 GMT

What else is in the label? If anything in the label contains those special characters, then the formatting tags will break. For example, this code

var ownlab1 = $feature.Site; var other = "This & that"; "<UND>" + Text(ownlab1) + "</UND>\n" + other;

results in this label

This code fixes it

var ownlab1 = $feature.Site; var other = Replace("This & that", "&", "&"); '<UND>'+Text(ownlab1)+'</UND>\n' + other;

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Wed, 04 Feb 2026 19:23:12 GMT

Turns out, this is only a problem when I use TextFormatting.NewLine. I tried with just one field and it worked fine.

Appears as though TextFormatting.NewLine does not play well with other formatting tags?

var ownlab = ownlab1 + TextFormatting.NewLine + ownlab2 + Textformatting.NewLine + ownlab3;

Re: Tags work inconsistently in Arcade

KenBuja — Wed, 04 Feb 2026 21:09:34 GMT

I'm not seeing that

I see it if I include a special character

For the labels that are broken, what are the values for ownlab2 and ownlab3?

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Thu, 05 Feb 2026 13:16:16 GMT

Thanks! I see no difference between values that are broken and those that are not. They are alphanumeric and I thought that was it (ie the code was confused by numbers as text) but I have seen, for example, '3234' and in a nearby parcel '<UND>3232</UND>' The maddening thing is that it is inconsistent. None of them have special characters or at least not visible special characters. Some get the underline and some don't. I've tried copying and pasting into Word to see if i could see any difference and I just can't.

It's a three line label and I tried it on the text in the second line - same thing - Some were underlined, some printed out the <UND></UND> tags.

I'm thinking either a bug or an Arcade/Text Formtting Tag incompatibility.

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Thu, 05 Feb 2026 13:25:08 GMT

For the labels that are broken, what are the values for ownlab2 and ownlab3?

I see what you're getting at here. Other lines may have the special characters! I'll check it out. Thank you!

Re: Tags work inconsistently in Arcade

RandyMcGregor_BMcD — Thu, 05 Feb 2026 13:43:51 GMT

Yes! That's it! I wasn't clueing in to the fact that the 2d and 3d lines might have special characters, because only the first line was underlined, but of course a special character anywhere in the label-text will throw the <UND> tags off. You DID explain this but It didn't register right away :-(. Thank you very much for your help and your patience. This will help us very much.