# Trimming an extended information field
**URL:** https://community.mp3tag.de/t/trimming-an-extended-information-field/65033
**Category:** Support
**Created:** [June 13, 2024, 3:51pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033 "2024-06-13T15:51:15Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Dotcom1970](https://community.mp3tag.de/u/Dotcom1970)
#### Post date: [June 13, 2024, 3:51pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/1 "2024-06-13T15:51:15Z")
I've noticed when pulling album catalogue numbers from discogs, and displaying them in a custom field, sometimes they have more than one.
e;g: TICK001CD, TICK001CD, TICK001CD, TICK001CD
How can I create a reg expression to grab that first catalogue number where commas separate multiples?
Currently, my custom field is as follows:
Name: CATALOGNUMBER
Value: $upper(%catalognumber%)
Field: %catalognumber%
---
### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [June 13, 2024, 3:59pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/2 "2024-06-13T15:59:11Z")
You want to reduce multiple appearances of the same content in CATALOGNUMBER to one entry?
Or do you want the first entry only, ignoring what other contents follow?
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### Author:  [@Dotcom1970](https://community.mp3tag.de/u/Dotcom1970)
#### Post date: [June 13, 2024, 4:01pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/3 "2024-06-13T16:01:04Z")
In that pictured example, they are all the same, but in others, they may be different - all I want is the first listed.
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [June 13, 2024, 4:18pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/4 "2024-06-13T16:18:01Z")
You could adapt
> [@RegExp to extract text before first comma](https://community.mp3tag.de/t/regexp-to-extract-text-before-first-comma/57083/2):
>
> This is not quite true if you use $regexp(%composer%,'^(.+?),.\*',$1) instead The potential section following the comma does not necessarily need the parenthesis if you do not want to use it anyway, so $2 is not mandatory. ... but there are so many ways to solve the problem.
and use
`$regexp(%CATALOGNUMBER%,'^(.+?),.*',$1)`
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### Author:  [@LyricsLover](https://community.mp3tag.de/u/LyricsLover)
#### Post date: [June 13, 2024, 4:24pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/5 "2024-06-13T16:24:56Z")
BTW:
The term "trimming" as used in your title question is not exactly what you want to do.
"Trimming" in the [scripting](https://docs.mp3tag.de/scripting/#string-functions) world means "to cut away leading or trailing whitespaces":
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### Author:  [@Dotcom1970](https://community.mp3tag.de/u/Dotcom1970)
#### Post date: [June 13, 2024, 4:31pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/6 "2024-06-13T16:31:13Z")
Apologies for using the wrong term. I'm very much a novice at this.
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [July 13, 2024, 4:31pm UTC](https://community.mp3tag.de/t/trimming-an-extended-information-field/65033/7 "2024-07-13T16:31:56Z")
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