# SeriesDescription characters '+' and '-' removed during OE2 ZIP export
**URL:** https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397
**Category:** General
**Created:** [February 11, 2026, 12:37pm UTC](https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397 "2026-02-11T12:37:10Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@jwooding-ox](https://discourse.orthanc-server.org/u/jwooding-ox)
#### Post date: [February 11, 2026, 12:37pm UTC](https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397/1 "2026-02-11T12:37:10Z")
Hi All,
I have a question regarding character handling during export from OE2.
We run Orthanc in a research environment. During MR experiments, researchers frequently use + and - characters in the SeriesDescription (0008,103E) to distinguish between small variations in experimental variables (e.g. increases or decreases).
When exporting a study via OE2 \> Export \> ZIP, the generated series directories are named based on the SeriesDescription. However, the + and - characters are removed from the folder names in the exported ZIP. I’ve included an example below to better illustrate this.
SeriesDescription
OE2 Export
This creates confusion for researchers because:
- It becomes difficult to distinguish between related series
- In some cases, folders appear duplicated as the only difference was this symbol
Importantly:
- The original DICOM files received by Orthanc contain the + and –
- The characters are present in the SeriesDescription on OE2
- The exported DICOM metadata still correctly contains the characters in (0008,103E)
- The issue appears to affect only the generated folder names in the ZIP export
I assume this may be intentional filename sanitisation, but I’m not aware of any filesystem that doesn’t support + or -.
Is anyone able to clarify:
1. Why are these characters removed from the generated folder names?
2. Is this behaviour configurable?
Environment:
- Orthanc version: 25.6.4
- Orthanc Explorer 2 version: 1.8.5
- Export method: OE2 \> Export ZIP \> extracted on Windows 11
Thanks in advance.
---
### Author:  [@alainmazy](https://discourse.orthanc-server.org/u/alainmazy)
#### Post date: [February 12, 2026, 5:15pm UTC](https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397/2 "2026-02-12T17:15:01Z")
Hi Jacob,
You are right, file/folder names in zip should support all characters but, right now, Orthanc keep only the alphanumeric characters.
I have added a [TODO](https://orthanc.uclouvain.be/hg/orthanc/rev/3adbd90885f9) in Orthanc to handle the full utf-8 character sets.
Best,
Alain.
---
### Author:  [@jodogne](https://discourse.orthanc-server.org/u/jodogne)
#### Post date: [February 13, 2026, 7:39am UTC](https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397/3 "2026-02-13T07:39:59Z")
Hello,
[Caution is needed here](https://en.wikipedia.org/wiki/ZIP_(file_format)#Internationalization_issues). Indeed, the original ZIP format doesn’t use UTF-8 but the CP437 encoding. [Support for UTF-8 was only introduced in 2006](https://en.wikipedia.org/wiki/ZIP_(file_format)#Version_history), apparently by adding a new “Unicode Path Extra Field”. I have had a brief look at the minizip 1.1 implementation that is internally used by Orthanc, and nothing indicates that this field is properly set. This is why Orthanc currently avoids non-ASCII characters in the generated ZIP archives. The first step would thus be to update minizip, which is not trivial.
Regards,
Sébastien-
---
### Author:  [@jwooding-ox](https://discourse.orthanc-server.org/u/jwooding-ox)
#### Post date: [February 16, 2026, 1:52pm UTC](https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397/4 "2026-02-16T13:52:20Z")
Hi Alain and Sébastien,
Thank you both for your replies.
I appreciate that this isn’t a straightforward change, especially given considerations and Sébastien outlined.
Thanks for adding it to the TODO list. This is more of a quality of life improvement for our research workflows rather than a critical issue. In the meantime, we can implement a simple workaround by simply avoiding these characters in the SeriesDescription.
Many thanks again for the clarification,
Jacob
---
### Author:  [@jodogne](https://discourse.orthanc-server.org/u/jodogne)
#### Post date: [March 1, 2026, 11:44am UTC](https://discourse.orthanc-server.org/t/seriesdescription-characters-and-removed-during-oe2-zip-export/6397/5 "2026-03-01T11:44:06Z")
Hello,
UTF-8 support in ZIP archives has just been implemented in Orthanc [by this changeset](https://orthanc.uclouvain.be/hg/orthanc/rev/9722dc04e6a6).
The new global configuration option `ZipUseUtf8` can be set to `true` to generate ZIP archives containing UTF-8 filenames. If the option is set to `false` (the default), only ASCII characters will be included, which largely corresponds to the behavior of Orthanc \<= 1.12.10. Note that `+` and `-` are now also allowed, which was not the case in earlier versions of Orthanc.
This global option can also be overridden on a per-archive basis by providing the `Utf8` argument to the `{...}/archive` and `/tools/create-archive` routes.
This development was made possible by the very recent release 1.3.2 of minizip (released on 2026-02-17), which is the first version of minizip that sets bit 11 of the ZIP header flag when the path is encoded in UTF-8 ([see their release notes](https://zlib.net/ChangeLog.txt)).
The reason `ZipUseUtf8` is set to `false` by default is that UTF-8 is still not well supported by many software. My tests were done on GNU/Linux using the `7z` command-line tool. Feedback from testing this new feature is welcome.
Kind regards,
Sébastien-